class Sequel::Dataset

A dataset represents an SQL query. Datasets can be used to select, insert, update and delete records.

Query results are always retrieved on demand, so a dataset can be kept around and reused indefinitely (datasets never cache results):

my_posts = DB[:posts].where(author: 'david') # no records are retrieved
my_posts.all # records are retrieved
my_posts.all # records are retrieved again

Datasets are frozen and use a functional style where modification methods return modified copies of the the dataset. This allows you to reuse datasets:

posts = DB[:posts]
davids_posts = posts.where(author: 'david')
old_posts = posts.where{stamp < Date.today - 7}
davids_old_posts = davids_posts.where{stamp < Date.today - 7}

Datasets are Enumerable objects, so they can be manipulated using many of the Enumerable methods, such as map and inject. Note that there are some methods that Dataset defines that override methods defined in Enumerable and result in different behavior, such as select and group_by.

For more information, see the “Dataset Basics” guide.

Constants

OPTS
TRUE_FREEZE

Whether Dataset#freeze can actually freeze datasets. True only on ruby 2.4+, as it requires clone(freeze: false)

1 - Methods that return modified datasets

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Constants

COLUMN_CHANGE_OPTS

The dataset options that require the removal of cached columns if changed.

CONDITIONED_JOIN_TYPES

These symbols have _join methods created (e.g. inner_join) that call join_table with the symbol, passing along the arguments and block from the method call.

EMPTY_ARRAY
EXTENSIONS

Hash of extension name symbols to callable objects to load the extension into the Dataset object (usually by extending it with a module defined in the extension).

EXTENSION_MODULES

Hash of extension name symbols to modules to load to implement the extension.

JOIN_METHODS

All methods that return modified datasets with a joined table added.

NON_SQL_OPTIONS

Which options don’t affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table.

QUERY_METHODS

Methods that return modified datasets

SIMPLE_SELECT_ALL_ALLOWED_FROM

From types allowed to be considered a simple_select_all

UNCONDITIONED_JOIN_TYPES

These symbols have _join methods created (e.g. natural_join). They accept a table argument and options hash which is passed to join_table, and they raise an error if called with a block.

Public Class Methods

register_extension(ext, mod=nil, &block) click to toggle source

Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should be a Module that will be included in the dataset’s class. This also registers a Database extension that will extend all of the database’s datasets.

   # File lib/sequel/dataset/query.rb
55 def self.register_extension(ext, mod=nil, &block)
56   if mod
57     raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block
58     if mod.is_a?(Module)
59       block = proc{|ds| ds.extend(mod)}
60       Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)}
61       Sequel.synchronize{EXTENSION_MODULES[ext] = mod}
62     else
63       block = mod
64     end
65   end
66 
67   unless mod.is_a?(Module)
68     Sequel::Deprecation.deprecate("Providing a block or non-module to Sequel::Dataset.register_extension is deprecated and support for it will be removed in Sequel 6.")
69   end
70 
71   Sequel.synchronize{EXTENSIONS[ext] = block}
72 end

Public Instance Methods

_clone(opts = nil || (return self))

Save original clone implementation, as some other methods need to call it internally.

Alias for: clone
clone(opts = nil || (return self)) click to toggle source

Returns a new clone of the dataset with the given options merged. If the options changed include options in COLUMN_CHANGE_OPTS, the cached columns are deleted. This method should generally not be called directly by user code.

Calls superclass method
   # File lib/sequel/dataset/query.rb
90 def clone(opts = nil || (return self))
91   # return self used above because clone is called by almost all
92   # other query methods, and it is the fastest approach
93   c = super(:freeze=>false)
94   c.opts.merge!(opts)
95   unless opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)}
96     c.clear_columns_cache
97   end
98   c.freeze
99 end
Also aliased as: _clone
distinct(*args, &block) click to toggle source

Returns a copy of the dataset with the SQL DISTINCT clause. The DISTINCT clause is used to remove duplicate rows from the output. If arguments are provided, uses a DISTINCT ON clause, in which case it will only be distinct on those columns, instead of all returned columns. If a block is given, it is treated as a virtual row block, similar to where. Raises an error if arguments are given and DISTINCT ON is not supported.

DB[:items].distinct # SQL: SELECT DISTINCT * FROM items
DB[:items].order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id
DB[:items].order(:id).distinct{func(:id)} # SQL: SELECT DISTINCT ON (func(id)) * FROM items ORDER BY id

There is support for emulating the DISTINCT ON support in MySQL, but it does not support the ORDER of the dataset, and also doesn’t work in many cases if the ONLY_FULL_GROUP_BY sql_mode is used, which is the default on MySQL 5.7.5+.

    # File lib/sequel/dataset/query.rb
129 def distinct(*args, &block)
130   virtual_row_columns(args, block)
131   if args.empty?
132     return self if opts[:distinct] == EMPTY_ARRAY
133     cached_dataset(:_distinct_ds){clone(:distinct => EMPTY_ARRAY)}
134   else
135     raise(InvalidOperation, "DISTINCT ON not supported") unless supports_distinct_on?
136     clone(:distinct => args.freeze)
137   end
138 end
except(dataset, opts=OPTS) click to toggle source

Adds an EXCEPT clause using a second dataset object. An EXCEPT compound dataset returns all rows in the current dataset that are not in the given dataset. Raises an InvalidOperation if the operation is not supported. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].except(DB[:other_items])
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS t1

DB[:items].except(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items EXCEPT ALL SELECT * FROM other_items

DB[:items].except(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
157 def except(dataset, opts=OPTS)
158   raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
159   raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
160   compound_clone(:except, dataset, opts)
161 end
exclude(*cond, &block) click to toggle source

Performs the inverse of Dataset#where. Note that if you have multiple filter conditions, this is not the same as a negation of all conditions.

DB[:items].exclude(category: 'software')
# SELECT * FROM items WHERE (category != 'software')

DB[:items].exclude(category: 'software', id: 3)
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))

Also note that SQL uses 3-valued boolean logic (true, false, NULL), so the inverse of a true condition is a false condition, and will still not match rows that were NULL originally. If you take the earlier example:

DB[:items].exclude(category: 'software')
# SELECT * FROM items WHERE (category != 'software')

Note that this does not match rows where category is NULL. This is because NULL is an unknown value, and you do not know whether or not the NULL category is software. You can explicitly specify how to handle NULL values if you want:

DB[:items].exclude(Sequel.~(category: nil) & {category: 'software'})
# SELECT * FROM items WHERE ((category IS NULL) OR (category != 'software'))
    # File lib/sequel/dataset/query.rb
187 def exclude(*cond, &block)
188   add_filter(:where, cond, true, &block)
189 end
exclude_having(*cond, &block) click to toggle source

Inverts the given conditions and adds them to the HAVING clause.

DB[:items].select_group(:name).exclude_having{count(name) < 2}
# SELECT name FROM items GROUP BY name HAVING (count(name) >= 2)

See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.

    # File lib/sequel/dataset/query.rb
198 def exclude_having(*cond, &block)
199   add_filter(:having, cond, true, &block)
200 end
extension(*exts) click to toggle source

Return a clone of the dataset loaded with the given dataset extensions. If no related extension file exists or the extension does not have specific support for Dataset objects, an error will be raised.

    # File lib/sequel/dataset/query.rb
206 def extension(*exts)
207   Sequel.extension(*exts)
208   mods = exts.map{|ext| Sequel.synchronize{EXTENSION_MODULES[ext]}}
209   if mods.all?
210     with_extend(*mods)
211   else
212     with_extend(DeprecatedSingletonClassMethods).extension(*exts)
213   end
214 end
filter(*cond, &block) click to toggle source

Alias for where.

    # File lib/sequel/dataset/query.rb
226 def filter(*cond, &block)
227   where(*cond, &block)
228 end
for_update() click to toggle source

Returns a cloned dataset with a :update lock style.

DB[:table].for_update # SELECT * FROM table FOR UPDATE
    # File lib/sequel/dataset/query.rb
233 def for_update
234    return self if opts[:lock] == :update
235   cached_dataset(:_for_update_ds){lock_style(:update)}
236 end
from(*source, &block) click to toggle source

Returns a copy of the dataset with the source changed. If no source is given, removes all tables. If multiple sources are given, it is the same as using a CROSS JOIN (cartesian product) between all tables. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].from # SQL: SELECT *
DB[:items].from(:blah) # SQL: SELECT * FROM blah
DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo
DB[:items].from{fun(arg)} # SQL: SELECT * FROM fun(arg)
    # File lib/sequel/dataset/query.rb
247 def from(*source, &block)
248   virtual_row_columns(source, block)
249   table_alias_num = 0
250   ctes = nil
251   source.map! do |s|
252     case s
253     when Dataset
254       if hoist_cte?(s)
255         ctes ||= []
256         ctes += s.opts[:with]
257         s = s.clone(:with=>nil)
258       end
259       SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
260     when Symbol
261       sch, table, aliaz = split_symbol(s)
262       if aliaz
263         s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table)
264         SQL::AliasedExpression.new(s, aliaz.to_sym)
265       else
266         s
267       end
268     else
269       s
270     end
271   end
272   o = {:from=>source.empty? ? nil : source.freeze}
273   o[:with] = ((opts[:with] || EMPTY_ARRAY) + ctes).freeze if ctes
274   o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
275   clone(o)
276 end
from_self(opts=OPTS) click to toggle source

Returns a dataset selecting from the current dataset. Options:

:alias

Controls the alias of the table

:column_aliases

Also aliases columns, using derived column lists. Only used in conjunction with :alias.

ds = DB[:items].order(:name).select(:id, :name)
# SELECT id,name FROM items ORDER BY name

ds.from_self
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS t1

ds.from_self(alias: :foo)
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo

ds.from_self(alias: :foo, column_aliases: [:c1, :c2])
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo(c1, c2)
    # File lib/sequel/dataset/query.rb
295 def from_self(opts=OPTS)
296   fs = {}
297   @opts.keys.each{|k| fs[k] = nil unless non_sql_option?(k)}
298   pr = proc do
299     c = clone(fs).from(opts[:alias] ? as(opts[:alias], opts[:column_aliases]) : self)
300     if cols = _columns
301       c.send(:columns=, cols)
302     end
303     c
304   end
305 
306   opts.empty? ? cached_dataset(:_from_self_ds, &pr) : pr.call
307 end
grep(columns, patterns, opts=OPTS) click to toggle source

Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions if the database supports that. Note that the total number of pattern matches will be Array(columns).length * Array(terms).length, which could cause performance issues.

Options (all are boolean):

:all_columns

All columns must be matched to any of the given patterns.

:all_patterns

All patterns must match at least one of the columns.

:case_insensitive

Use a case insensitive pattern match (the default is case sensitive if the database supports it).

If both :all_columns and :all_patterns are true, all columns must match all patterns.

Examples:

dataset.grep(:a, '%test%')
# SELECT * FROM items WHERE (a LIKE '%test%' ESCAPE '\')

dataset.grep([:a, :b], %w'%test% foo')
# SELECT * FROM items WHERE ((a LIKE '%test%' ESCAPE '\') OR (a LIKE 'foo' ESCAPE '\')
#   OR (b LIKE '%test%' ESCAPE '\') OR (b LIKE 'foo' ESCAPE '\'))

dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true)
# SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (b LIKE '%foo%' ESCAPE '\'))
#   AND ((a LIKE '%bar%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\')))

dataset.grep([:a, :b], %w'%foo% %bar%', all_columns: true)
# SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (a LIKE '%bar%' ESCAPE '\'))
#   AND ((b LIKE '%foo%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\')))

dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true, all_columns: true)
# SELECT * FROM a WHERE ((a LIKE '%foo%' ESCAPE '\') AND (b LIKE '%foo%' ESCAPE '\')
#   AND (a LIKE '%bar%' ESCAPE '\') AND (b LIKE '%bar%' ESCAPE '\'))
    # File lib/sequel/dataset/query.rb
344 def grep(columns, patterns, opts=OPTS)
345   column_op = opts[:all_columns] ? :AND : :OR
346   if opts[:all_patterns]
347     conds = Array(patterns).map do |pat|
348       SQL::BooleanExpression.new(column_op, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
349     end
350     where(SQL::BooleanExpression.new(:AND, *conds))
351   else
352     conds = Array(columns).map do |c|
353       SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
354     end
355     where(SQL::BooleanExpression.new(column_op, *conds))
356   end
357 end
group(*columns, &block) click to toggle source

Returns a copy of the dataset with the results grouped by the value of the given columns. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].group(:id) # SELECT * FROM items GROUP BY id
DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name
DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)
    # File lib/sequel/dataset/query.rb
366 def group(*columns, &block)
367   virtual_row_columns(columns, block)
368   clone(:group => (columns.compact.empty? ? nil : columns.freeze))
369 end
group_and_count(*columns, &block) click to toggle source

Returns a dataset grouped by the given column with count by group. Column aliases may be supplied, and will be included in the select clause. If a block is given, it is treated as a virtual row block, similar to where.

Examples:

DB[:items].group_and_count(:name).all
# SELECT name, count(*) AS count FROM items GROUP BY name
# => [{:name=>'a', :count=>1}, ...]

DB[:items].group_and_count(:first_name, :last_name).all
# SELECT first_name, last_name, count(*) AS count FROM items GROUP BY first_name, last_name
# => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...]

DB[:items].group_and_count(Sequel[:first_name].as(:name)).all
# SELECT first_name AS name, count(*) AS count FROM items GROUP BY first_name
# => [{:name=>'a', :count=>1}, ...]

DB[:items].group_and_count{substr(:first_name, 1, 1).as(:initial)}.all
# SELECT substr(first_name, 1, 1) AS initial, count(*) AS count FROM items GROUP BY substr(first_name, 1, 1)
# => [{:initial=>'a', :count=>1}, ...]
    # File lib/sequel/dataset/query.rb
397 def group_and_count(*columns, &block)
398   select_group(*columns, &block).select_append(COUNT_OF_ALL_AS_COUNT)
399 end
group_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the list of existing columns to group on. If no existing columns are present this method simply sets the columns as the initial ones to group on.

DB[:items].group_append(:b) # SELECT * FROM items GROUP BY b
DB[:items].group(:a).group_append(:b) # SELECT * FROM items GROUP BY a, b
    # File lib/sequel/dataset/query.rb
407 def group_append(*columns, &block)
408   columns = @opts[:group] + columns if @opts[:group]
409   group(*columns, &block)
410 end
group_by(*columns, &block) click to toggle source

Alias of group

    # File lib/sequel/dataset/query.rb
372 def group_by(*columns, &block)
373   group(*columns, &block)
374 end
group_cube() click to toggle source

Adds the appropriate CUBE syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
413 def group_cube
414   raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
415   clone(:group_options=>:cube)
416 end
group_rollup() click to toggle source

Adds the appropriate ROLLUP syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
419 def group_rollup
420   raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
421   clone(:group_options=>:rollup)
422 end
grouping_sets() click to toggle source

Adds the appropriate GROUPING SETS syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
425 def grouping_sets
426   raise Error, "GROUP BY GROUPING SETS not supported on #{db.database_type}" unless supports_grouping_sets?
427   clone(:group_options=>:"grouping sets")
428 end
having(*cond, &block) click to toggle source

Returns a copy of the dataset with the HAVING conditions changed. See where for argument types.

DB[:items].group(:sum).having(sum: 10)
# SELECT * FROM items GROUP BY sum HAVING (sum = 10)
    # File lib/sequel/dataset/query.rb
434 def having(*cond, &block)
435   add_filter(:having, cond, &block)
436 end
intersect(dataset, opts=OPTS) click to toggle source

Adds an INTERSECT clause using a second dataset object. An INTERSECT compound dataset returns all rows in both the current dataset and the given dataset. Raises an InvalidOperation if the operation is not supported. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].intersect(DB[:other_items])
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS t1

DB[:items].intersect(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items INTERSECT ALL SELECT * FROM other_items

DB[:items].intersect(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
455 def intersect(dataset, opts=OPTS)
456   raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
457   raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
458   compound_clone(:intersect, dataset, opts)
459 end
invert() click to toggle source

Inverts the current WHERE and HAVING clauses. If there is neither a WHERE or HAVING clause, adds a WHERE clause that is always false.

DB[:items].where(category: 'software').invert
# SELECT * FROM items WHERE (category != 'software')

DB[:items].where(category: 'software', id: 3).invert
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))

See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.

    # File lib/sequel/dataset/query.rb
472 def invert
473   cached_dataset(:_invert_ds) do
474     having, where = @opts.values_at(:having, :where)
475     if having.nil? && where.nil?
476       where(false)
477     else
478       o = {}
479       o[:having] = SQL::BooleanExpression.invert(having) if having
480       o[:where] = SQL::BooleanExpression.invert(where) if where
481       clone(o)
482     end
483   end
484 end
join(*args, &block) click to toggle source

Alias of inner_join

    # File lib/sequel/dataset/query.rb
487 def join(*args, &block)
488   inner_join(*args, &block)
489 end
join_table(type, table, expr=nil, options=OPTS) { |table_name, last_alias, opts || EMPTY_ARRAY| ... } click to toggle source

Returns a joined dataset. Not usually called directly, users should use the appropriate join method (e.g. join, left_join, natural_join, cross_join) which fills in the type argument.

Takes the following arguments:

type

The type of join to do (e.g. :inner)

table

table to join into the current dataset. Generally one of the following types:

String, Symbol

identifier used as table or view name

Dataset

a subselect is performed with an alias of tN for some value of N

SQL::Function

set returning function

SQL::AliasedExpression

already aliased expression. Uses given alias unless overridden by the :table_alias option.

expr

conditions used when joining, depends on type:

Hash, Array of pairs

Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table (or the :implicit_qualifier option). To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.

Array

If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.

nil

If a block is not given, doesn’t use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses an ON clause based on the block, see below.

otherwise

Treats the argument as a filter expression, so strings are considered literal, symbols specify boolean columns, and Sequel expressions can be used. Uses a JOIN with an ON clause.

options

a hash of options, with the following keys supported:

:table_alias

Override the table alias used when joining. In general you shouldn’t use this option, you should provide the appropriate SQL::AliasedExpression as the table argument.

:implicit_qualifier

The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.

:join_using

Force the using of JOIN USING, even if expr is not an array of symbols.

:reset_implicit_qualifier

Can set to false to ignore this join when future joins determine qualifier for implicit conditions.

:qualify

Can be set to false to not do any implicit qualification. Can be set to :deep to use the Qualifier AST Transformer, which will attempt to qualify subexpressions of the expression tree. Can be set to :symbol to only qualify symbols. Defaults to the value of default_join_table_qualification.

block

The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause. Unlike where, this block is not treated as a virtual row block.

Examples:

DB[:a].join_table(:cross, :b)
# SELECT * FROM a CROSS JOIN b

DB[:a].join_table(:inner, DB[:b], c: d)
# SELECT * FROM a INNER JOIN (SELECT * FROM b) AS t1 ON (t1.c = a.d)

DB[:a].join_table(:left, Sequel[:b].as(:c), [:d])
# SELECT * FROM a LEFT JOIN b AS c USING (d)

DB[:a].natural_join(:b).join_table(:inner, :c) do |ta, jta, js|
  (Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>DB.from(js.first.table).select(:g)}
end
# SELECT * FROM a NATURAL JOIN b INNER JOIN c
#   ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
    # File lib/sequel/dataset/query.rb
551 def join_table(type, table, expr=nil, options=OPTS, &block)
552   if hoist_cte?(table)
553     s, ds = hoist_cte(table)
554     return s.join_table(type, ds, expr, options, &block)
555   end
556 
557   using_join = options[:join_using] || (expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)})
558   if using_join && !supports_join_using?
559     h = {}
560     expr.each{|e| h[e] = e}
561     return join_table(type, table, h, options)
562   end
563 
564   table_alias = options[:table_alias]
565 
566   if table.is_a?(SQL::AliasedExpression)
567     table_expr = if table_alias
568       SQL::AliasedExpression.new(table.expression, table_alias, table.columns)
569     else
570       table
571     end
572     table = table_expr.expression
573     table_name = table_alias = table_expr.alias
574   elsif table.is_a?(Dataset)
575     if table_alias.nil?
576       table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
577       table_alias = dataset_alias(table_alias_num)
578     end
579     table_name = table_alias
580     table_expr = SQL::AliasedExpression.new(table, table_alias)
581   else
582     table, implicit_table_alias = split_alias(table)
583     table_alias ||= implicit_table_alias
584     table_name = table_alias || table
585     table_expr = table_alias ? SQL::AliasedExpression.new(table, table_alias) : table
586   end
587 
588   join = if expr.nil? and !block
589     SQL::JoinClause.new(type, table_expr)
590   elsif using_join
591     raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
592     SQL::JoinUsingClause.new(expr, type, table_expr)
593   else
594     last_alias = options[:implicit_qualifier] || @opts[:last_joined_table] || first_source_alias
595     qualify_type = options[:qualify]
596     if Sequel.condition_specifier?(expr)
597       expr = expr.map do |k, v|
598         qualify_type = default_join_table_qualification if qualify_type.nil?
599         case qualify_type
600         when false
601           nil # Do no qualification
602         when :deep
603           k = Sequel::Qualifier.new(table_name).transform(k)
604           v = Sequel::Qualifier.new(last_alias).transform(v)
605         else
606           k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
607           v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
608         end
609         [k,v]
610       end
611       expr = SQL::BooleanExpression.from_value_pairs(expr)
612     end
613     if block
614       expr2 = yield(table_name, last_alias, @opts[:join] || EMPTY_ARRAY)
615       expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
616     end
617     SQL::JoinOnClause.new(expr, type, table_expr)
618   end
619 
620   opts = {:join => ((@opts[:join] || EMPTY_ARRAY) + [join]).freeze}
621   opts[:last_joined_table] = table_name unless options[:reset_implicit_qualifier] == false
622   opts[:num_dataset_sources] = table_alias_num if table_alias_num
623   clone(opts)
624 end
lateral() click to toggle source

Marks this dataset as a lateral dataset. If used in another dataset’s FROM or JOIN clauses, it will surround the subquery with LATERAL to enable it to deal with previous tables in the query:

DB.from(:a, DB[:b].where(Sequel[:a][:c]=>Sequel[:b][:d]).lateral)
# SELECT * FROM a, LATERAL (SELECT * FROM b WHERE (a.c = b.d))
    # File lib/sequel/dataset/query.rb
645 def lateral
646   return self if opts[:lateral]
647   cached_dataset(:_lateral_ds){clone(:lateral=>true)}
648 end
limit(l, o = (no_offset = true; nil)) click to toggle source

If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset. To use an offset without a limit, pass nil as the first argument.

DB[:items].limit(10) # SELECT * FROM items LIMIT 10
DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20
DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10
DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10
DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
    # File lib/sequel/dataset/query.rb
660 def limit(l, o = (no_offset = true; nil))
661   return from_self.limit(l, o) if @opts[:sql]
662 
663   if l.is_a?(Range)
664     no_offset = false
665     o = l.first
666     l = l.last - l.first + (l.exclude_end? ? 0 : 1)
667   end
668   l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
669   if l.is_a?(Integer)
670     raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
671   end
672 
673   ds = clone(:limit=>l)
674   ds = ds.offset(o) unless no_offset
675   ds
676 end
lock_style(style) click to toggle source

Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. You should never pass a string to this method that is derived from user input, as that can lead to SQL injection.

A symbol may be used for database independent locking behavior, but all supported symbols have separate methods (e.g. for_update).

DB[:items].lock_style('FOR SHARE NOWAIT')
# SELECT * FROM items FOR SHARE NOWAIT
DB[:items].lock_style('FOR UPDATE OF table1 SKIP LOCKED')
# SELECT * FROM items FOR UPDATE OF table1 SKIP LOCKED
    # File lib/sequel/dataset/query.rb
690 def lock_style(style)
691   clone(:lock => style)
692 end
merge_delete(&block) click to toggle source

Return a dataset with a WHEN MATCHED THEN DELETE clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

merge_delete
# WHEN MATCHED THEN DELETE

merge_delete{a > 30}
# WHEN MATCHED AND (a > 30) THEN DELETE
    # File lib/sequel/dataset/query.rb
703 def merge_delete(&block)
704   _merge_when(:type=>:delete, &block)
705 end
merge_insert(*values, &block) click to toggle source

Return a dataset with a WHEN NOT MATCHED THEN INSERT clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

The arguments provided can be any arguments that would be accepted by insert.

merge_insert(i1: :i2, a: Sequel[:b]+11)
# WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))

merge_insert(:i2, Sequel[:b]+11){a > 30}
# WHEN NOT MATCHED AND (a > 30) THEN INSERT VALUES (i2, (b + 11))
    # File lib/sequel/dataset/query.rb
719 def merge_insert(*values, &block)
720   _merge_when(:type=>:insert, :values=>values, &block)
721 end
merge_update(values, &block) click to toggle source

Return a dataset with a WHEN MATCHED THEN UPDATE clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20)
# WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

merge_update(i1: :i2){a > 30}
# WHEN MATCHED AND (a > 30) THEN UPDATE SET i1 = i2
    # File lib/sequel/dataset/query.rb
732 def merge_update(values, &block)
733   _merge_when(:type=>:update, :values=>values, &block)
734 end
merge_using(source, join_condition) click to toggle source

Return a dataset with the source and join condition to use for the MERGE statement.

merge_using(:m2, i1: :i2)
# USING m2 ON (i1 = i2)
    # File lib/sequel/dataset/query.rb
740 def merge_using(source, join_condition)
741   clone(:merge_using => [source, join_condition].freeze)
742 end
naked() click to toggle source

Returns a cloned dataset without a row_proc.

ds = DB[:items].with_row_proc(:invert.to_proc)
ds.all # => [{2=>:id}]
ds.naked.all # => [{:id=>2}]
    # File lib/sequel/dataset/query.rb
749 def naked
750   return self unless opts[:row_proc]
751   cached_dataset(:_naked_ds){with_row_proc(nil)}
752 end
nowait() click to toggle source

Returns a copy of the dataset that will raise a DatabaseLockTimeout instead of waiting for rows that are locked by another transaction

DB[:items].for_update.nowait
# SELECT * FROM items FOR UPDATE NOWAIT
    # File lib/sequel/dataset/query.rb
759 def nowait
760   return self if opts[:nowait]
761   cached_dataset(:_nowait_ds) do
762     raise(Error, 'This dataset does not support raises errors instead of waiting for locked rows') unless supports_nowait?
763     clone(:nowait=>true)
764   end
765 end
offset(o) click to toggle source

Returns a copy of the dataset with a specified order. Can be safely combined with limit. If you call limit with an offset, it will override the offset if you’ve called offset first.

DB[:items].offset(10) # SELECT * FROM items OFFSET 10
    # File lib/sequel/dataset/query.rb
772 def offset(o)
773   o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
774   if o.is_a?(Integer)
775     raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
776   end
777   clone(:offset => o)
778 end
or(*cond, &block) click to toggle source

Adds an alternate filter to an existing WHERE clause using OR. If there is no WHERE clause, then the default is WHERE true, and OR would be redundant, so return the dataset in that case.

DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b
DB[:items].or(:b) # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
786 def or(*cond, &block)
787   if @opts[:where].nil?
788     self
789   else
790     add_filter(:where, cond, false, :OR, &block)
791   end
792 end
order(*columns, &block) click to toggle source

Returns a copy of the dataset with the order changed. If the dataset has an existing order, it is ignored and overwritten with this order. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, such as SQL functions. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].order(:name) # SELECT * FROM items ORDER BY name
DB[:items].order(:a, :b) # SELECT * FROM items ORDER BY a, b
DB[:items].order(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b
DB[:items].order(Sequel[:a] + :b) # SELECT * FROM items ORDER BY (a + b)
DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC
DB[:items].order(Sequel.asc(:name, nulls: :last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST
DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC
DB[:items].order(nil) # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
808 def order(*columns, &block)
809   virtual_row_columns(columns, block)
810   clone(:order => (columns.compact.empty?) ? nil : columns.freeze)
811 end
order_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the order columns added to the end of the existing order.

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_append(:b) # SELECT * FROM items ORDER BY a, b
    # File lib/sequel/dataset/query.rb
818 def order_append(*columns, &block)
819   columns = @opts[:order] + columns if @opts[:order]
820   order(*columns, &block)
821 end
order_by(*columns, &block) click to toggle source

Alias of order

    # File lib/sequel/dataset/query.rb
824 def order_by(*columns, &block)
825   order(*columns, &block)
826 end
order_more(*columns, &block) click to toggle source

Alias of order_append.

    # File lib/sequel/dataset/query.rb
829 def order_more(*columns, &block)
830   order_append(*columns, &block)
831 end
order_prepend(*columns, &block) click to toggle source

Returns a copy of the dataset with the order columns added to the beginning of the existing order.

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
    # File lib/sequel/dataset/query.rb
838 def order_prepend(*columns, &block)
839   ds = order(*columns, &block)
840   @opts[:order] ? ds.order_append(*@opts[:order]) : ds
841 end
qualify(table=(cache=true; first_source)) click to toggle source

Qualify to the given table, or first source if no table is given.

DB[:items].where(id: 1).qualify
# SELECT items.* FROM items WHERE (items.id = 1)

DB[:items].where(id: 1).qualify(:i)
# SELECT i.* FROM items WHERE (i.id = 1)
    # File lib/sequel/dataset/query.rb
850 def qualify(table=(cache=true; first_source))
851   o = @opts
852   return self if o[:sql]
853 
854   pr = proc do
855     h = {}
856     (o.keys & QUALIFY_KEYS).each do |k|
857       h[k] = qualified_expression(o[k], table)
858     end
859     h[:select] = [SQL::ColumnAll.new(table)].freeze if !o[:select] || o[:select].empty?
860     clone(h)
861   end
862 
863   cache ? cached_dataset(:_qualify_ds, &pr) : pr.call
864 end
returning(*values) click to toggle source

Modify the RETURNING clause, only supported on a few databases. If returning is used, instead of insert returning the autogenerated primary key or update/delete returning the number of modified rows, results are returned using fetch_rows.

DB[:items].returning # RETURNING *
DB[:items].returning(nil) # RETURNING NULL
DB[:items].returning(:id, :name) # RETURNING id, name

DB[:items].returning.insert(a: 1) do |hash|
  # hash for each row inserted, with values for all columns
end
DB[:items].returning.update(a: 1) do |hash|
  # hash for each row updated, with values for all columns
end
DB[:items].returning.delete(a: 1) do |hash|
  # hash for each row deleted, with values for all columns
end
    # File lib/sequel/dataset/query.rb
884 def returning(*values)
885   if values.empty?
886     return self if opts[:returning] == EMPTY_ARRAY
887     cached_dataset(:_returning_ds) do
888       raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
889       clone(:returning=>EMPTY_ARRAY)
890     end
891   else
892     raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
893     clone(:returning=>values.freeze)
894   end
895 end
reverse(*order, &block) click to toggle source

Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.

DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC
DB[:items].reverse{foo(bar)} # SELECT * FROM items ORDER BY foo(bar) DESC
DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC
DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC
    # File lib/sequel/dataset/query.rb
904 def reverse(*order, &block)
905   if order.empty? && !block
906     cached_dataset(:_reverse_ds){order(*invert_order(@opts[:order]))}
907   else
908     virtual_row_columns(order, block)
909     order(*invert_order(order.empty? ? @opts[:order] : order.freeze))
910   end
911 end
reverse_order(*order, &block) click to toggle source

Alias of reverse

    # File lib/sequel/dataset/query.rb
914 def reverse_order(*order, &block)
915   reverse(*order, &block)
916 end
select(*columns, &block) click to toggle source

Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to where.

DB[:items].select(:a) # SELECT a FROM items
DB[:items].select(:a, :b) # SELECT a, b FROM items
DB[:items].select{[a, sum(b)]} # SELECT a, sum(b) FROM items
    # File lib/sequel/dataset/query.rb
925 def select(*columns, &block)
926   virtual_row_columns(columns, block)
927   clone(:select => columns.freeze)
928 end
select_all(*tables) click to toggle source

Returns a copy of the dataset selecting the wildcard if no arguments are given. If arguments are given, treat them as tables and select all columns (using the wildcard) from each table.

DB[:items].select(:a).select_all # SELECT * FROM items
DB[:items].select_all(:items) # SELECT items.* FROM items
DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
    # File lib/sequel/dataset/query.rb
937 def select_all(*tables)
938   if tables.empty?
939     return self unless opts[:select]
940     cached_dataset(:_select_all_ds){clone(:select => nil)}
941   else
942     select(*tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze)
943   end
944 end
select_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.

DB[:items].select(:a).select(:b) # SELECT b FROM items
DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items
DB[:items].select_append(:b) # SELECT *, b FROM items
    # File lib/sequel/dataset/query.rb
953 def select_append(*columns, &block)
954   virtual_row_columns(columns, block)
955   select(*(_current_select(true) + columns))
956 end
select_group(*columns, &block) click to toggle source

Set both the select and group clauses with the given columns. Column aliases may be supplied, and will be included in the select clause. This also takes a virtual row block similar to where.

DB[:items].select_group(:a, :b)
# SELECT a, b FROM items GROUP BY a, b

DB[:items].select_group(Sequel[:c].as(:a)){f(c2)}
# SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)
    # File lib/sequel/dataset/query.rb
967 def select_group(*columns, &block)
968   virtual_row_columns(columns, block)
969   select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
970 end
select_more(*columns, &block) click to toggle source

Alias for select_append.

    # File lib/sequel/dataset/query.rb
973 def select_more(*columns, &block)
974   select_append(*columns, &block)
975 end
select_prepend(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.

DB[:items].select(:a).select(:b) # SELECT b FROM items
DB[:items].select(:a).select_prepend(:b) # SELECT b, a FROM items
DB[:items].select_prepend(:b) # SELECT b, * FROM items
    # File lib/sequel/dataset/query.rb
984 def select_prepend(*columns, &block)
985   virtual_row_columns(columns, block)
986   select(*(columns + _current_select(false)))
987 end
server(servr) click to toggle source

Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.

DB[:items].all # Uses the :read_only or :default server
DB[:items].delete # Uses the :default server
DB[:items].server(:blah).delete # Uses the :blah server
     # File lib/sequel/dataset/query.rb
 998 def server(servr)
 999   clone(:server=>servr)
1000 end
server?(server) click to toggle source

If the database uses sharding and the current dataset has not had a server set, return a cloned dataset that uses the given server. Otherwise, return the receiver directly instead of returning a clone.

     # File lib/sequel/dataset/query.rb
1005 def server?(server)
1006   if db.sharded? && !opts[:server]
1007     server(server)
1008   else
1009     self
1010   end
1011 end
skip_limit_check() click to toggle source

Specify that the check for limits/offsets when updating/deleting be skipped for the dataset.

     # File lib/sequel/dataset/query.rb
1014 def skip_limit_check
1015   return self if opts[:skip_limit_check]
1016   cached_dataset(:_skip_limit_check_ds) do
1017     clone(:skip_limit_check=>true)
1018   end
1019 end
skip_locked() click to toggle source

Skip locked rows when returning results from this dataset.

     # File lib/sequel/dataset/query.rb
1022 def skip_locked
1023   return self if opts[:skip_locked]
1024   cached_dataset(:_skip_locked_ds) do
1025     raise(Error, 'This dataset does not support skipping locked rows') unless supports_skip_locked?
1026     clone(:skip_locked=>true)
1027   end
1028 end
unfiltered() click to toggle source

Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.

DB[:items].group(:a).having(a: 1).where(:b).unfiltered
# SELECT * FROM items GROUP BY a
     # File lib/sequel/dataset/query.rb
1034 def unfiltered
1035   return self unless opts[:where] || opts[:having]
1036   cached_dataset(:_unfiltered_ds){clone(:where => nil, :having => nil)}
1037 end
ungrouped() click to toggle source

Returns a copy of the dataset with no grouping (GROUP or HAVING clause) applied.

DB[:items].group(:a).having(a: 1).where(:b).ungrouped
# SELECT * FROM items WHERE b
     # File lib/sequel/dataset/query.rb
1043 def ungrouped
1044   return self unless opts[:group] || opts[:having]
1045   cached_dataset(:_ungrouped_ds){clone(:group => nil, :having => nil)}
1046 end
union(dataset, opts=OPTS) click to toggle source

Adds a UNION clause using a second dataset object. A UNION compound dataset returns all rows in either the current dataset or the given dataset. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use UNION ALL instead of UNION, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].union(DB[:other_items])
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS t1

DB[:items].union(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items UNION ALL SELECT * FROM other_items

DB[:items].union(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
     # File lib/sequel/dataset/query.rb
1064 def union(dataset, opts=OPTS)
1065   compound_clone(:union, dataset, opts)
1066 end
unlimited() click to toggle source

Returns a copy of the dataset with no limit or offset.

DB[:items].limit(10, 20).unlimited # SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1071 def unlimited
1072   return self unless opts[:limit] || opts[:offset]
1073   cached_dataset(:_unlimited_ds){clone(:limit=>nil, :offset=>nil)}
1074 end
unordered() click to toggle source

Returns a copy of the dataset with no order.

DB[:items].order(:a).unordered # SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1079 def unordered
1080   return self unless opts[:order]
1081   cached_dataset(:_unordered_ds){clone(:order=>nil)}
1082 end
where(*cond, &block) click to toggle source

Returns a copy of the dataset with the given WHERE conditions imposed upon it.

Accepts the following argument types:

Hash, Array of pairs

list of equality/inclusion expressions

Symbol

taken as a boolean column argument (e.g. WHERE active)

Sequel::SQL::BooleanExpression, Sequel::LiteralString

an existing condition expression, probably created using the Sequel expression filter DSL.

where also accepts a block, which should return one of the above argument types, and is treated the same way. This block yields a virtual row object, which is easy to use to create identifiers and functions. For more details on the virtual row support, see the “Virtual Rows” guide

If both a block and regular argument are provided, they get ANDed together.

Examples:

DB[:items].where(id: 3)
# SELECT * FROM items WHERE (id = 3)

DB[:items].where(Sequel.lit('price < ?', 100))
# SELECT * FROM items WHERE price < 100

DB[:items].where([[:id, [1,2,3]], [:id, 0..10]])
# SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))

DB[:items].where(Sequel.lit('price < 100'))
# SELECT * FROM items WHERE price < 100

DB[:items].where(:active)
# SELECT * FROM items WHERE :active

DB[:items].where{price < 100}
# SELECT * FROM items WHERE (price < 100)

Multiple where calls can be chained for scoping:

software = dataset.where(category: 'software').where{price < 100}
# SELECT * FROM items WHERE ((category = 'software') AND (price < 100))

See the “Dataset Filtering” guide for more examples and details.

     # File lib/sequel/dataset/query.rb
1126 def where(*cond, &block)
1127   add_filter(:where, cond, &block)
1128 end
window(name, opts) click to toggle source

Return a clone of the dataset with an addition named window that can be referenced in window functions. See Sequel::SQL::Window for a list of options that can be passed in. Example:

DB[:items].window(:w, partition: :c1, order: :c2)
# SELECT * FROM items WINDOW w AS (PARTITION BY c1 ORDER BY c2)
     # File lib/sequel/dataset/query.rb
1136 def window(name, opts)
1137   clone(:window=>((@opts[:window]||EMPTY_ARRAY) + [[name, SQL::Window.new(opts)].freeze]).freeze)
1138 end
with(name, dataset, opts=OPTS) click to toggle source

Add a common table expression (CTE) with the given name and a dataset that defines the CTE. A common table expression acts as an inline view for the query.

Options:

:args

Specify the arguments/columns for the CTE, should be an array of symbols.

:recursive

Specify that this is a recursive CTE

:materialized

Set to false to force inlining of the CTE, or true to force not inlining the CTE (PostgreSQL 12+/SQLite 3.35+).

DB[:items].with(:items, DB[:syx].where(Sequel[:name].like('A%')))
# WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%' ESCAPE '\')) SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1151 def with(name, dataset, opts=OPTS)
1152   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1153   if hoist_cte?(dataset)
1154     s, ds = hoist_cte(dataset)
1155     s.with(name, ds, opts)
1156   else
1157     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:name=>name, :dataset=>dataset)]).freeze)
1158   end
1159 end
with_extend(*mods, &block) click to toggle source

Create a subclass of the receiver’s class, and include the given modules into it. If a block is provided, a DatasetModule is created using the block and is included into the subclass. Create an instance of the subclass using the same db and opts, so that the returned dataset operates similarly to a clone extended with the given modules. This approach is used to avoid singleton classes, which significantly improves performance.

Note that like Object#extend, when multiple modules are provided as arguments the subclass includes the modules in reverse order.

     # File lib/sequel/dataset/query.rb
1240 def with_extend(*mods, &block)
1241   c = Class.new(self.class)
1242   c.include(*mods) unless mods.empty?
1243   c.include(DatasetModule.new(&block)) if block
1244   o = c.freeze.allocate
1245   o.instance_variable_set(:@db, @db)
1246   o.instance_variable_set(:@opts, @opts)
1247   o.instance_variable_set(:@cache, {})
1248   if cols = cache_get(:_columns)
1249     o.send(:columns=, cols)
1250   end
1251   o.freeze
1252 end
with_recursive(name, nonrecursive, recursive, opts=OPTS) click to toggle source

Add a recursive common table expression (CTE) with the given name, a dataset that defines the nonrecursive part of the CTE, and a dataset that defines the recursive part of the CTE.

Options:

:args

Specify the arguments/columns for the CTE, should be an array of symbols.

:union_all

Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts.

PostgreSQL 14+ Options:

:cycle

Stop recursive searching when a cycle is detected. Includes two columns in the result of the CTE, a cycle column indicating whether a cycle was detected for the current row, and a path column for the path traversed to get to the current row. If given, must be a hash with the following keys:

:columns

(required) The column or array of columns to use to detect a cycle. If the value of these columns match columns already traversed, then a cycle is detected, and recursive searching will not traverse beyond the cycle (the CTE will include the row where the cycle was detected).

:cycle_column

The name of the cycle column in the output, defaults to :is_cycle.

:cycle_value

The value of the cycle column in the output if the current row was detected as a cycle, defaults to true.

:noncycle_value

The value of the cycle column in the output if the current row was not detected as a cycle, defaults to false. Only respected if :cycle_value is given.

:path_column

The name of the path column in the output, defaults to :path.

:search

Include an order column in the result of the CTE that allows for breadth or depth first searching. If given, must be a hash with the following keys:

:by

(required) The column or array of columns to search by.

:order_column

The name of the order column in the output, defaults to :ordercol.

:type

Set to :breadth to use breadth-first searching (depth-first searching is the default).

DB[:t].with_recursive(:t,
  DB[:i1].select(:id, :parent_id).where(parent_id: nil),
  DB[:i1].join(:t, id: :parent_id).select(Sequel[:i1][:id], Sequel[:i1][:parent_id]),
  args: [:id, :parent_id])

# WITH RECURSIVE t(id, parent_id) AS (
#   SELECT id, parent_id FROM i1 WHERE (parent_id IS NULL)
#   UNION ALL
#   SELECT i1.id, i1.parent_id FROM i1 INNER JOIN t ON (t.id = i1.parent_id)
# ) SELECT * FROM t

DB[:t].with_recursive(:t,
  DB[:i1].where(parent_id: nil),
  DB[:i1].join(:t, id: :parent_id).select_all(:i1),
  search: {by: :id, type: :breadth},
  cycle: {columns: :id, cycle_value: 1, noncycle_value: 2})

# WITH RECURSIVE t AS (
#     SELECT * FROM i1 WHERE (parent_id IS NULL)
#     UNION ALL
#     (SELECT i1.* FROM i1 INNER JOIN t ON (t.id = i1.parent_id))
#   )
#   SEARCH BREADTH FIRST BY id SET ordercol
#   CYCLE id SET is_cycle TO 1 DEFAULT 2 USING path
# SELECT * FROM t
     # File lib/sequel/dataset/query.rb
1217 def with_recursive(name, nonrecursive, recursive, opts=OPTS)
1218   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1219   if hoist_cte?(nonrecursive)
1220     s, ds = hoist_cte(nonrecursive)
1221     s.with_recursive(name, ds, recursive, opts)
1222   elsif hoist_cte?(recursive)
1223     s, ds = hoist_cte(recursive)
1224     s.with_recursive(name, nonrecursive, ds, opts)
1225   else
1226     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]).freeze)
1227   end
1228 end
with_row_proc(callable) click to toggle source

Returns a cloned dataset with the given row_proc.

ds = DB[:items]
ds.all # => [{:id=>2}]
ds.with_row_proc(:invert.to_proc).all # => [{2=>:id}]
     # File lib/sequel/dataset/query.rb
1269 def with_row_proc(callable)
1270   clone(:row_proc=>callable)
1271 end
with_sql(sql, *args) click to toggle source

Returns a copy of the dataset with the static SQL used. This is useful if you want to keep the same row_proc/graph, but change the SQL used to custom SQL.

DB[:items].with_sql('SELECT * FROM foo') # SELECT * FROM foo

You can use placeholders in your SQL and provide arguments for those placeholders:

DB[:items].with_sql('SELECT ? FROM foo', 1) # SELECT 1 FROM foo

You can also provide a method name and arguments to call to get the SQL:

DB[:items].with_sql(:insert_sql, b: 1) # INSERT INTO items (b) VALUES (1)

Note that datasets that specify custom SQL using this method will generally ignore future dataset methods that modify the SQL used, as specifying custom SQL overrides Sequel’s SQL generator. You should probably limit yourself to the following dataset methods when using this method, or use the implicit_subquery extension:

  • each

  • all

  • single_record (if only one record could be returned)

  • single_value (if only one record could be returned, and a single column is selected)

  • map

  • as_hash

  • to_hash

  • to_hash_groups

  • delete (if a DELETE statement)

  • update (if an UPDATE statement, with no arguments)

  • insert (if an INSERT statement, with no arguments)

  • truncate (if a TRUNCATE statement, with no arguments)

     # File lib/sequel/dataset/query.rb
1303 def with_sql(sql, *args)
1304   if sql.is_a?(Symbol)
1305     sql = public_send(sql, *args)
1306   else
1307     sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
1308   end
1309   clone(:sql=>sql)
1310 end

Protected Instance Methods

compound_clone(type, dataset, opts) click to toggle source

Add the dataset to the list of compounds

     # File lib/sequel/dataset/query.rb
1315 def compound_clone(type, dataset, opts)
1316   if dataset.is_a?(Dataset) && dataset.opts[:with] && !supports_cte_in_compounds?
1317     s, ds = hoist_cte(dataset)
1318     return s.compound_clone(type, ds, opts)
1319   end
1320   ds = compound_from_self.clone(:compounds=>(Array(@opts[:compounds]).map(&:dup) + [[type, dataset.compound_from_self, opts[:all]].freeze]).freeze)
1321   opts[:from_self] == false ? ds : ds.from_self(opts)
1322 end
options_overlap(opts) click to toggle source

Return true if the dataset has a non-nil value for any key in opts.

     # File lib/sequel/dataset/query.rb
1325 def options_overlap(opts)
1326   !(@opts.map{|k,v| k unless v.nil?}.compact & opts).empty?
1327 end
simple_select_all?() click to toggle source

Whether this dataset is a simple select from an underlying table, such as:

SELECT * FROM table
SELECT table.* FROM table
     # File lib/sequel/dataset/query.rb
1336 def simple_select_all?
1337   return false unless (f = @opts[:from]) && f.length == 1
1338   o = @opts.reject{|k,v| v.nil? || non_sql_option?(k)}
1339   from = f.first
1340   from = from.expression if from.is_a?(SQL::AliasedExpression)
1341 
1342   if SIMPLE_SELECT_ALL_ALLOWED_FROM.any?{|x| from.is_a?(x)}
1343     case o.length
1344     when 1
1345       true
1346     when 2
1347       (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
1348     else
1349       false
1350     end
1351   else
1352     false
1353   end
1354 end

Private Instance Methods

_current_select(allow_plain_wildcard) click to toggle source

A frozen array for the currently selected columns.

     # File lib/sequel/dataset/query.rb
1376 def _current_select(allow_plain_wildcard)
1377   cur_sel = @opts[:select]
1378 
1379   if !cur_sel || cur_sel.empty?
1380     cur_sel = if allow_plain_wildcard && supports_select_all_and_column?
1381       [WILDCARD].freeze
1382     else
1383       _current_select_column_all
1384     end
1385   elsif !allow_plain_wildcard && cur_sel.include?(WILDCARD)
1386     cur_sel = cur_sel.dup
1387     index = cur_sel.index(WILDCARD)
1388     cur_sel.delete(WILDCARD)
1389     _current_select_column_all.each_with_index do |ca, i|
1390       cur_sel.insert(index+i, ca)
1391     end
1392     cur_sel.freeze
1393   end
1394 
1395   cur_sel
1396 end
_current_select_column_all() click to toggle source

An array of SQL::ColumnAll objects for all FROM and JOIN tables. Used for select_append and select_prepend.

     # File lib/sequel/dataset/query.rb
1400 def _current_select_column_all
1401   tables = Array(@opts[:from]) + Array(@opts[:join])
1402   tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze
1403 end
_extension!(exts) click to toggle source

Load the extensions into the receiver, without checking if the receiver is frozen.

     # File lib/sequel/dataset/query.rb
1361 def _extension!(exts)
1362   Sequel.extension(*exts)
1363   exts.each do |ext|
1364     if pr = Sequel.synchronize{EXTENSIONS[ext]}
1365       pr.call(self)
1366     else
1367       raise(Error, "Extension #{ext} does not have specific support handling individual datasets (try: Sequel.extension #{ext.inspect})")
1368     end
1369   end
1370   self
1371 end
_invert_filter(cond, invert) click to toggle source

If invert is true, invert the condition.

     # File lib/sequel/dataset/query.rb
1406 def _invert_filter(cond, invert)
1407   if invert
1408     SQL::BooleanExpression.invert(cond)
1409   else
1410     cond
1411   end
1412 end
_merge_when(hash, &block) click to toggle source

Append to the current MERGE WHEN clauses. Mutates the hash to add the conditions, if a virtual row block is passed.

     # File lib/sequel/dataset/query.rb
1416 def _merge_when(hash, &block)
1417   hash[:conditions] = Sequel.virtual_row(&block) if block
1418 
1419   if merge_when = @opts[:merge_when]
1420     clone(:merge_when => (merge_when.dup << hash.freeze).freeze)
1421   else
1422     clone(:merge_when => [hash.freeze].freeze)
1423   end
1424 end
add_filter(clause, cond, invert=false, combine=:AND, &block) click to toggle source

Add the given filter condition. Arguments:

clause

Symbol or which SQL clause to effect, should be :where or :having

cond

The filter condition to add

invert

Whether the condition should be inverted (true or false)

combine

How to combine the condition with an existing condition, should be :AND or :OR

     # File lib/sequel/dataset/query.rb
1431 def add_filter(clause, cond, invert=false, combine=:AND, &block)
1432   if cond == EMPTY_ARRAY && !block
1433     raise Error, "must provide an argument to a filtering method if not passing a block"
1434   end
1435   
1436   cond = cond.first if cond.size == 1
1437 
1438   empty = cond == OPTS || cond == EMPTY_ARRAY
1439 
1440   if empty && !block
1441     self 
1442   else
1443     if cond == nil
1444       cond = Sequel::NULL
1445     end
1446     if empty && block
1447       cond = nil
1448     end
1449 
1450     cond = _invert_filter(filter_expr(cond, &block), invert)
1451     cond = SQL::BooleanExpression.new(combine, @opts[clause], cond) if @opts[clause]
1452 
1453     if cond.nil?
1454       cond = Sequel::NULL
1455     end
1456 
1457     clone(clause => cond)
1458   end
1459 end
default_join_table_qualification() click to toggle source

The default :qualify option to use for join tables if one is not specified.

     # File lib/sequel/dataset/query.rb
1462 def default_join_table_qualification
1463   :symbol
1464 end
default_server() click to toggle source

Return self if the dataset already has a server, or a cloned dataset with the default server otherwise.

     # File lib/sequel/dataset/query.rb
1537 def default_server
1538   server?(:default)
1539 end
filter_expr(expr = nil, &block) click to toggle source

SQL expression object based on the expr type. See where.

     # File lib/sequel/dataset/query.rb
1467 def filter_expr(expr = nil, &block)
1468   expr = nil if expr == EMPTY_ARRAY
1469 
1470   if block
1471     cond = filter_expr(Sequel.virtual_row(&block))
1472     cond = SQL::BooleanExpression.new(:AND, filter_expr(expr), cond) if expr
1473     return cond
1474   end
1475 
1476   case expr
1477   when Hash
1478     SQL::BooleanExpression.from_value_pairs(expr)
1479   when Array
1480     if Sequel.condition_specifier?(expr)
1481       SQL::BooleanExpression.from_value_pairs(expr)
1482     else
1483       raise Error, "Invalid filter expression: #{expr.inspect}"
1484     end
1485   when LiteralString
1486     LiteralString.new("(#{expr})")
1487   when Numeric, SQL::NumericExpression, SQL::StringExpression, Proc, String
1488     raise Error, "Invalid filter expression: #{expr.inspect}"
1489   when TrueClass, FalseClass
1490     if supports_where_true?
1491       SQL::BooleanExpression.new(:NOOP, expr)
1492     elsif expr
1493       SQL::Constants::SQLTRUE
1494     else
1495       SQL::Constants::SQLFALSE
1496     end
1497   when PlaceholderLiteralizer::Argument
1498     expr.transform{|v| filter_expr(v)}
1499   when SQL::PlaceholderLiteralString
1500     expr.with_parens
1501   else
1502     expr
1503   end
1504 end
hoist_cte(ds) click to toggle source

Return two datasets, the first a clone of the receiver with the WITH clause from the given dataset added to it, and the second a clone of the given dataset with the WITH clause removed.

     # File lib/sequel/dataset/query.rb
1509 def hoist_cte(ds)
1510   [clone(:with => ((opts[:with] || EMPTY_ARRAY) + ds.opts[:with]).freeze), ds.clone(:with => nil)]
1511 end
hoist_cte?(ds) click to toggle source

Whether CTEs need to be hoisted from the given ds into the current ds.

     # File lib/sequel/dataset/query.rb
1514 def hoist_cte?(ds)
1515   ds.is_a?(Dataset) && ds.opts[:with] && !supports_cte_in_subqueries?
1516 end
invert_order(order) click to toggle source

Inverts the given order by breaking it into a list of column references and inverting them.

DB[:items].invert_order([Sequel.desc(:id)]]) #=> [Sequel.asc(:id)]
DB[:items].invert_order([:category, Sequel.desc(:price)]) #=> [Sequel.desc(:category), Sequel.asc(:price)]
     # File lib/sequel/dataset/query.rb
1523 def invert_order(order)
1524   return unless order
1525   order.map do |f|
1526     case f
1527     when SQL::OrderedExpression
1528       f.invert
1529     else
1530       SQL::OrderedExpression.new(f)
1531     end
1532   end
1533 end
non_sql_option?(key) click to toggle source

Whether the given option key does not affect the generated SQL.

     # File lib/sequel/dataset/query.rb
1542 def non_sql_option?(key)
1543   NON_SQL_OPTIONS.include?(key)
1544 end
virtual_row_columns(columns, block) click to toggle source

Treat the block as a virtual_row block if not nil and add the resulting columns to the columns array (modifies columns).

     # File lib/sequel/dataset/query.rb
1548 def virtual_row_columns(columns, block)
1549   if block
1550     v = Sequel.virtual_row(&block)
1551     if v.is_a?(Array)
1552       columns.concat(v)
1553     else
1554       columns << v
1555     end
1556   end
1557 end

2 - Methods that execute code on the database

↑ top

Constants

ACTION_METHODS

Action methods defined by Sequel that execute code on the database.

COLUMNS_CLONE_OPTIONS

The clone options to use when retrieving columns for a dataset.

COUNT_SELECT
EMPTY_SELECT

Public Instance Methods

<<(arg) click to toggle source

Inserts the given argument into the database. Returns self so it can be used safely when chaining:

DB[:items] << {id: 0, name: 'Zero'} << DB[:old_items].select(:id, name)
   # File lib/sequel/dataset/actions.rb
28 def <<(arg)
29   insert(arg)
30   self
31 end
[](*conditions) click to toggle source

Returns the first record matching the conditions. Examples:

DB[:table][id: 1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=>1}
   # File lib/sequel/dataset/actions.rb
37 def [](*conditions)
38   raise(Error, 'You cannot call Dataset#[] with an integer or with no arguments') if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
39   first(*conditions)
40 end
all(&block) click to toggle source

Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.

DB[:table].all # SELECT * FROM table
# => [{:id=>1, ...}, {:id=>2, ...}, ...]

# Iterate over all rows in the table
DB[:table].all{|row| p row}
   # File lib/sequel/dataset/actions.rb
50 def all(&block)
51   _all(block){|a| each{|r| a << r}}
52 end
as_hash(key_column, value_column = nil, opts = OPTS) click to toggle source

Returns a hash with one column used as key and another used as value. If rows have duplicate values for the key column, the latter row(s) will overwrite the value of the previous row(s). If the value_column is not given or nil, uses the entire hash as the value.

DB[:table].as_hash(:id, :name) # SELECT * FROM table
# {1=>'Jim', 2=>'Bob', ...}

DB[:table].as_hash(:id) # SELECT * FROM table
# {1=>{:id=>1, :name=>'Jim'}, 2=>{:id=>2, :name=>'Bob'}, ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].as_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table
# {[1, 3]=>['Jim', 'bo'], [2, 4]=>['Bob', 'be'], ...}

DB[:table].as_hash([:id, :name]) # SELECT * FROM table
# {[1, 'Jim']=>{:id=>1, :name=>'Jim'}, [2, 'Bob']=>{:id=>2, :name=>'Bob'}, ...}

Options:

:all

Use all instead of each to retrieve the objects

:hash

The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc.

    # File lib/sequel/dataset/actions.rb
847 def as_hash(key_column, value_column = nil, opts = OPTS)
848   h = opts[:hash] || {}
849   meth = opts[:all] ? :all : :each
850   if value_column
851     return naked.as_hash(key_column, value_column, opts) if row_proc
852     if value_column.is_a?(Array)
853       if key_column.is_a?(Array)
854         public_send(meth){|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
855       else
856         public_send(meth){|r| h[r[key_column]] = r.values_at(*value_column)}
857       end
858     else
859       if key_column.is_a?(Array)
860         public_send(meth){|r| h[r.values_at(*key_column)] = r[value_column]}
861       else
862         public_send(meth){|r| h[r[key_column]] = r[value_column]}
863       end
864     end
865   elsif key_column.is_a?(Array)
866     public_send(meth){|r| h[key_column.map{|k| r[k]}] = r}
867   else
868     public_send(meth){|r| h[r[key_column]] = r}
869   end
870   h
871 end
avg(arg=(no_arg = true), &block) click to toggle source

Returns the average value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1
# => 3
DB[:table].avg{function(column)} # SELECT avg(function(column)) FROM table LIMIT 1
# => 1
   # File lib/sequel/dataset/actions.rb
61 def avg(arg=(no_arg = true), &block)
62   arg = Sequel.virtual_row(&block) if no_arg
63   _aggregate(:avg, arg)
64 end
columns() click to toggle source

Returns the columns in the result set in order as an array of symbols. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to retrieve a single row in order to get the columns.

If you are looking for all columns for a single table and maybe some information about each column (e.g. database type), see Database#schema.

DB[:table].columns
# => [:id, :name]
   # File lib/sequel/dataset/actions.rb
75 def columns
76   _columns || columns!
77 end
columns!() click to toggle source

Ignore any cached column information and perform a query to retrieve a row in order to get the columns.

DB[:table].columns!
# => [:id, :name]
   # File lib/sequel/dataset/actions.rb
84 def columns!
85   ds = clone(COLUMNS_CLONE_OPTIONS)
86   ds.each{break}
87 
88   if cols = ds.cache[:_columns]
89     self.columns = cols
90   else
91     []
92   end
93 end
count(arg=(no_arg=true), &block) click to toggle source

Returns the number of records in the dataset. If an argument is provided, it is used as the argument to count. If a block is provided, it is treated as a virtual row, and the result is used as the argument to count.

DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1
# => 3
DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1
# => 2
DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1
# => 1
    # File lib/sequel/dataset/actions.rb
108 def count(arg=(no_arg=true), &block)
109   if no_arg && !block
110     cached_dataset(:_count_ds) do
111       aggregate_dataset.select(COUNT_SELECT).single_value_ds
112     end.single_value!.to_i
113   else
114     if block
115       if no_arg
116         arg = Sequel.virtual_row(&block)
117       else
118         raise Error, 'cannot provide both argument and block to Dataset#count'
119       end
120     end
121 
122     _aggregate(:count, arg)
123   end
124 end
delete(&block) click to toggle source

Deletes the records in the dataset, returning the number of records deleted.

DB[:table].delete # DELETE * FROM table
# => 3

Some databases support using multiple tables in a DELETE query. This requires multiple FROM tables (JOINs can also be used). As multiple FROM tables use an implicit CROSS JOIN, you should make sure your WHERE condition uses the appropriate filters for the FROM tables:

DB.from(:a, :b).join(:c, :d=>Sequel[:b][:e]).where{{a[:f]=>b[:g], a[:id]=>c[:h]}}.
  delete
# DELETE FROM a
# USING b
# INNER JOIN c ON (c.d = b.e)
# WHERE ((a.f = b.g) AND (a.id = c.h))
    # File lib/sequel/dataset/actions.rb
142 def delete(&block)
143   sql = delete_sql
144   if uses_returning?(:delete)
145     returning_fetch_rows(sql, &block)
146   else
147     execute_dui(sql)
148   end
149 end
each() { |call| ... } click to toggle source

Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.

DB[:table].each{|row| p row} # SELECT * FROM table

Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, you should use all instead of each for the outer queries, or use a separate thread or shard inside each.

    # File lib/sequel/dataset/actions.rb
160 def each
161   if rp = row_proc
162     fetch_rows(select_sql){|r| yield rp.call(r)}
163   else
164     fetch_rows(select_sql){|r| yield r}
165   end
166   self
167 end
empty?() click to toggle source

Returns true if no records exist in the dataset, false otherwise

DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1
# => false
    # File lib/sequel/dataset/actions.rb
175 def empty?
176   cached_dataset(:_empty_ds) do
177     (@opts[:sql] ? from_self : self).single_value_ds.unordered.select(EMPTY_SELECT)
178   end.single_value!.nil?
179 end
first(*args, &block) click to toggle source

Returns the first matching record if no arguments are given. If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If any other type of argument(s) is passed, it is treated as a filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything.

If there are no records in the dataset, returns nil (or an empty array if an integer argument is given).

Examples:

DB[:table].first # SELECT * FROM table LIMIT 1
# => {:id=>7}

DB[:table].first(2) # SELECT * FROM table LIMIT 2
# => [{:id=>6}, {:id=>4}]

DB[:table].first(id: 2) # SELECT * FROM table WHERE (id = 2) LIMIT 1
# => {:id=>2}

DB[:table].first(Sequel.lit("id = 3")) # SELECT * FROM table WHERE (id = 3) LIMIT 1
# => {:id=>3}

DB[:table].first(Sequel.lit("id = ?", 4)) # SELECT * FROM table WHERE (id = 4) LIMIT 1
# => {:id=>4}

DB[:table].first{id > 2} # SELECT * FROM table WHERE (id > 2) LIMIT 1
# => {:id=>5}

DB[:table].first(Sequel.lit("id > ?", 4)){id < 6} # SELECT * FROM table WHERE ((id > 4) AND (id < 6)) LIMIT 1
# => {:id=>5}

DB[:table].first(2){id < 2} # SELECT * FROM table WHERE (id < 2) LIMIT 2
# => [{:id=>1}]
    # File lib/sequel/dataset/actions.rb
216 def first(*args, &block)
217   case args.length
218   when 0
219     unless block
220       return single_record
221     end
222   when 1
223     arg = args[0]
224     if arg.is_a?(Integer)
225       res = if block
226         if loader = cached_placeholder_literalizer(:_first_integer_cond_loader) do |pl|
227             where(pl.arg).limit(pl.arg)
228           end
229 
230           loader.all(filter_expr(&block), arg)
231         else
232           where(&block).limit(arg).all
233         end
234       else
235         if loader = cached_placeholder_literalizer(:_first_integer_loader) do |pl|
236            limit(pl.arg)
237           end
238 
239           loader.all(arg)
240         else
241           limit(arg).all
242         end
243       end
244 
245       return res
246     end
247     where_args = args
248     args = arg
249   end
250 
251   if loader = cached_where_placeholder_literalizer(where_args||args, block, :_first_cond_loader) do |pl|
252       _single_record_ds.where(pl.arg)
253     end
254 
255     loader.first(filter_expr(args, &block))
256   else
257     _single_record_ds.where(args, &block).single_record!
258   end
259 end
first!(*args, &block) click to toggle source

Calls first. If first returns nil (signaling that no row matches), raise a Sequel::NoMatchingRow exception.

    # File lib/sequel/dataset/actions.rb
263 def first!(*args, &block)
264   first(*args, &block) || raise(Sequel::NoMatchingRow.new(self))
265 end
get(column=(no_arg=true; nil), &block) click to toggle source

Return the column value for the first matching record in the dataset. Raises an error if both an argument and block is given.

DB[:table].get(:id) # SELECT id FROM table LIMIT 1
# => 3

ds.get{sum(id)} # SELECT sum(id) AS v FROM table LIMIT 1
# => 6

You can pass an array of arguments to return multiple arguments, but you must make sure each element in the array has an alias that Sequel can determine:

DB[:table].get([:id, :name]) # SELECT id, name FROM table LIMIT 1
# => [3, 'foo']

DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1
# => [6, 'foo']
    # File lib/sequel/dataset/actions.rb
285 def get(column=(no_arg=true; nil), &block)
286   ds = naked
287   if block
288     raise(Error, 'Must call Dataset#get with an argument or a block, not both') unless no_arg
289     ds = ds.select(&block)
290     column = ds.opts[:select]
291     column = nil if column.is_a?(Array) && column.length < 2
292   else
293     case column
294     when Array
295       ds = ds.select(*column)
296     when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
297       if loader = cached_placeholder_literalizer(:_get_loader) do |pl|
298           ds.single_value_ds.select(pl.arg)
299         end
300 
301         return loader.get(column)
302       end
303 
304       ds = ds.select(column)
305     else
306       if loader = cached_placeholder_literalizer(:_get_alias_loader) do |pl|
307           ds.single_value_ds.select(Sequel.as(pl.arg, :v))
308         end
309 
310         return loader.get(column)
311       end
312 
313       ds = ds.select(Sequel.as(column, :v))
314     end
315   end
316 
317   if column.is_a?(Array)
318    if r = ds.single_record
319      r.values_at(*hash_key_symbols(column))
320    end
321   else
322     ds.single_value
323   end
324 end
import(columns, values, opts=OPTS) click to toggle source

Inserts multiple records into the associated table. This method can be used to efficiently insert a large number of records into a table in a single query if the database supports it. Inserts are automatically wrapped in a transaction if necessary.

This method is called with a columns array and an array of value arrays:

DB[:table].import([:x, :y], [[1, 2], [3, 4]])
# INSERT INTO table (x, y) VALUES (1, 2)
# INSERT INTO table (x, y) VALUES (3, 4)

or, if the database supports it:

# INSERT INTO table (x, y) VALUES (1, 2), (3, 4)

This method also accepts a dataset instead of an array of value arrays:

DB[:table].import([:x, :y], DB[:table2].select(:a, :b))
# INSERT INTO table (x, y) SELECT a, b FROM table2

Options:

:commit_every

Open a new transaction for every given number of records. For example, if you provide a value of 50, will commit after every 50 records. When a transaction is not required, this option controls the maximum number of values to insert with a single statement; it does not force the use of a transaction.

:return

When this is set to :primary_key, returns an array of autoincremented primary key values for the rows inserted. This does not have an effect if values is a Dataset.

:server

Set the server/shard to use for the transaction and insert queries.

:skip_transaction

Do not use a transaction even when using multiple INSERT queries.

:slice

Same as :commit_every, :commit_every takes precedence.

    # File lib/sequel/dataset/actions.rb
362 def import(columns, values, opts=OPTS)
363   return insert(columns, values) if values.is_a?(Dataset)
364 
365   return if values.empty?
366   raise(Error, 'Using Sequel::Dataset#import with an empty column array is not allowed') if columns.empty?
367   ds = opts[:server] ? server(opts[:server]) : self
368   
369   if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice))
370     offset = 0
371     rows = []
372     while offset < values.length
373       rows << ds._import(columns, values[offset, slice_size], opts)
374       offset += slice_size
375     end
376     rows.flatten
377   else
378     ds._import(columns, values, opts)
379   end
380 end
insert(*values, &block) click to toggle source

Inserts values into the associated table. The returned value is generally the value of the autoincremented primary key for the inserted row, assuming that a single row is inserted and the table has an autoincrementing primary key.

insert handles a number of different argument formats:

no arguments or single empty hash

Uses DEFAULT VALUES

single hash

Most common format, treats keys as columns and values as values

single array

Treats entries as values, with no columns

two arrays

Treats first array as columns, second array as values

single Dataset

Treats as an insert based on a selection from the dataset given, with no columns

array and dataset

Treats as an insert based on a selection from the dataset given, with the columns given by the array.

Examples:

DB[:items].insert
# INSERT INTO items DEFAULT VALUES

DB[:items].insert({})
# INSERT INTO items DEFAULT VALUES

DB[:items].insert([1,2,3])
# INSERT INTO items VALUES (1, 2, 3)

DB[:items].insert([:a, :b], [1,2])
# INSERT INTO items (a, b) VALUES (1, 2)

DB[:items].insert(a: 1, b: 2)
# INSERT INTO items (a, b) VALUES (1, 2)

DB[:items].insert(DB[:old_items])
# INSERT INTO items SELECT * FROM old_items

DB[:items].insert([:a, :b], DB[:old_items])
# INSERT INTO items (a, b) SELECT * FROM old_items
    # File lib/sequel/dataset/actions.rb
418 def insert(*values, &block)
419   sql = insert_sql(*values)
420   if uses_returning?(:insert)
421     returning_fetch_rows(sql, &block)
422   else
423     execute_insert(sql)
424   end
425 end
last(*args, &block) click to toggle source

Reverses the order and then runs first with the given arguments and block. Note that this will not necessarily give you the last record in the dataset, unless you have an unambiguous order. If there is not currently an order for this dataset, raises an Error.

DB[:table].order(:id).last # SELECT * FROM table ORDER BY id DESC LIMIT 1
# => {:id=>10}

DB[:table].order(Sequel.desc(:id)).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2
# => [{:id=>1}, {:id=>2}]
    # File lib/sequel/dataset/actions.rb
437 def last(*args, &block)
438   raise(Error, 'No order specified') unless @opts[:order]
439   reverse.first(*args, &block)
440 end
map(column=nil, &block) click to toggle source

Maps column values for each record in the dataset (if an argument is given) or performs the stock mapping functionality of Enumerable otherwise. Raises an Error if both an argument and block are given.

DB[:table].map(:id) # SELECT * FROM table
# => [1, 2, 3, ...]

DB[:table].map{|r| r[:id] * 2} # SELECT * FROM table
# => [2, 4, 6, ...]

You can also provide an array of column names:

DB[:table].map([:id, :name]) # SELECT * FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
Calls superclass method
    # File lib/sequel/dataset/actions.rb
456 def map(column=nil, &block)
457   if column
458     raise(Error, 'Must call Dataset#map with either an argument or a block, not both') if block
459     return naked.map(column) if row_proc
460     if column.is_a?(Array)
461       super(){|r| r.values_at(*column)}
462     else
463       super(){|r| r[column]}
464     end
465   else
466     super(&block)
467   end
468 end
max(arg=(no_arg = true), &block) click to toggle source

Returns the maximum value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1
# => 10
DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1
# => 7
    # File lib/sequel/dataset/actions.rb
477 def max(arg=(no_arg = true), &block)
478   arg = Sequel.virtual_row(&block) if no_arg
479   _aggregate(:max, arg)
480 end
merge() click to toggle source

Execute a MERGE statement, which allows for INSERT, UPDATE, and DELETE behavior in a single query, based on whether rows from a source table match rows in the current table, based on the join conditions.

Unless the dataset uses static SQL, to use merge, you must first have called merge_using to specify the merge source and join conditions. You will then likely to call one or more of the following methods to specify MERGE behavior by adding WHEN [NOT] MATCHED clauses:

The WHEN [NOT] MATCHED clauses are added to the SQL in the order these methods were called on the dataset. If none of these methods are called, an error is raised.

Example:

DB[:m1]
  merge_using(:m2, i1: :i2).
  merge_insert(i1: :i2, a: Sequel[:b]+11).
  merge_delete{a > 30}.
  merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20).
  merge

SQL:

MERGE INTO m1 USING m2 ON (i1 = i2)
WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))
WHEN MATCHED AND (a > 30) THEN DELETE
WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

On PostgreSQL, two additional merge methods are supported, for the PostgreSQL-specific DO NOTHING syntax.

  • merge_do_nothing_when_matched

  • merge_do_nothing_when_not_matched

This method is supported on Oracle, but Oracle’s MERGE support is non-standard, and has the following issues:

  • DELETE clause requires UPDATE clause

  • DELETE clause requires a condition

  • DELETE clause only affects rows updated by UPDATE clause

    # File lib/sequel/dataset/actions.rb
527 def merge
528   execute_ddl(merge_sql)
529 end
min(arg=(no_arg = true), &block) click to toggle source

Returns the minimum value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1
# => 1
DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1
# => 0
    # File lib/sequel/dataset/actions.rb
538 def min(arg=(no_arg = true), &block)
539   arg = Sequel.virtual_row(&block) if no_arg
540   _aggregate(:min, arg)
541 end
multi_insert(hashes, opts=OPTS) click to toggle source

This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:

DB[:table].multi_insert([{x: 1}, {x: 2}])
# INSERT INTO table (x) VALUES (1)
# INSERT INTO table (x) VALUES (2)

Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.

This respects the same options as import.

    # File lib/sequel/dataset/actions.rb
555 def multi_insert(hashes, opts=OPTS)
556   return if hashes.empty?
557   columns = hashes.first.keys
558   import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
559 end
paged_each(opts=OPTS) { || ... } click to toggle source

Yields each row in the dataset, but internally uses multiple queries as needed to process the entire result set without keeping all rows in the dataset in memory, even if the underlying driver buffers all query results in memory.

Because this uses multiple queries internally, in order to remain consistent, it also uses a transaction internally. Additionally, to work correctly, the dataset must have unambiguous order. Using an ambiguous order can result in an infinite loop, as well as subtler bugs such as yielding duplicate rows or rows being skipped.

Sequel checks that the datasets using this method have an order, but it cannot ensure that the order is unambiguous.

Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, use a separate thread or shard inside paged_each.

Options:

:rows_per_fetch

The number of rows to fetch per query. Defaults to 1000.

:strategy

The strategy to use for paging of results. By default this is :offset, for using an approach with a limit and offset for every page. This can be set to :filter, which uses a limit and a filter that excludes rows from previous pages. In order for this strategy to work, you must be selecting the columns you are ordering by, and none of the columns can contain NULLs. Note that some Sequel adapters have optimized implementations that will use cursors or streaming regardless of the :strategy option used.

:filter_values

If the strategy: :filter option is used, this option should be a proc that accepts the last retrieved row for the previous page and an array of ORDER BY expressions, and returns an array of values relating to those expressions for the last retrieved row. You will need to use this option if your ORDER BY expressions are not simple columns, if they contain qualified identifiers that would be ambiguous unqualified, if they contain any identifiers that are aliased in SELECT, and potentially other cases.

:skip_transaction

Do not use a transaction. This can be useful if you want to prevent a lock on the database table, at the expense of consistency.

Examples:

DB[:table].order(:id).paged_each{|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table ORDER BY id LIMIT 1000 OFFSET 1000
# ...

DB[:table].order(:id).paged_each(rows_per_fetch: 100){|row| }
# SELECT * FROM table ORDER BY id LIMIT 100
# SELECT * FROM table ORDER BY id LIMIT 100 OFFSET 100
# ...

DB[:table].order(:id).paged_each(strategy: :filter){|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
# ...

DB[:table].order(:id).paged_each(strategy: :filter,
  filter_values: lambda{|row, exprs| [row[:id]]}){|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
# ...
    # File lib/sequel/dataset/actions.rb
618 def paged_each(opts=OPTS)
619   unless @opts[:order]
620     raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
621   end
622   unless defined?(yield)
623     return enum_for(:paged_each, opts)
624   end
625 
626   total_limit = @opts[:limit]
627   offset = @opts[:offset]
628   if server = @opts[:server]
629     opts = Hash[opts]
630     opts[:server] = server
631   end
632 
633   rows_per_fetch = opts[:rows_per_fetch] || 1000
634   strategy = if offset || total_limit
635     :offset
636   else
637     opts[:strategy] || :offset
638   end
639 
640   db.transaction(opts) do
641     case strategy
642     when :filter
643       filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}}
644       base_ds = ds = limit(rows_per_fetch)
645       while ds
646         last_row = nil
647         ds.each do |row|
648           last_row = row
649           yield row
650         end
651         ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row)
652       end
653     else
654       offset ||= 0
655       num_rows_yielded = rows_per_fetch
656       total_rows = 0
657 
658       while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
659         if total_limit && total_rows + rows_per_fetch > total_limit
660           rows_per_fetch = total_limit - total_rows
661         end
662 
663         num_rows_yielded = 0
664         limit(rows_per_fetch, offset).each do |row|
665           num_rows_yielded += 1
666           total_rows += 1 if total_limit
667           yield row
668         end
669 
670         offset += rows_per_fetch
671       end
672     end
673   end
674 
675   self
676 end
select_hash(key_column, value_column, opts = OPTS) click to toggle source

Returns a hash with key_column values as keys and value_column values as values. Similar to as_hash, but only selects the columns given. Like as_hash, it accepts an optional :hash parameter, into which entries will be merged.

DB[:table].select_hash(:id, :name)
# SELECT id, name FROM table
# => {1=>'a', 2=>'b', ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].select_hash([:id, :foo], [:name, :bar])
# SELECT id, foo, name, bar FROM table
# => {[1, 3]=>['a', 'c'], [2, 4]=>['b', 'd'], ...}

When using this method, you must be sure that each expression has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
696 def select_hash(key_column, value_column, opts = OPTS)
697   _select_hash(:as_hash, key_column, value_column, opts)
698 end
select_hash_groups(key_column, value_column, opts = OPTS) click to toggle source

Returns a hash with key_column values as keys and an array of value_column values. Similar to to_hash_groups, but only selects the columns given. Like to_hash_groups, it accepts an optional :hash parameter, into which entries will be merged.

DB[:table].select_hash_groups(:name, :id)
# SELECT id, name FROM table
# => {'a'=>[1, 4, ...], 'b'=>[2, ...], ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].select_hash_groups([:first, :middle], [:last, :id])
# SELECT first, middle, last, id FROM table
# => {['a', 'b']=>[['c', 1], ['d', 2], ...], ...}

When using this method, you must be sure that each expression has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
717 def select_hash_groups(key_column, value_column, opts = OPTS)
718   _select_hash(:to_hash_groups, key_column, value_column, opts)
719 end
select_map(column=nil, &block) click to toggle source

Selects the column given (either as an argument or as a block), and returns an array of all values of that column in the dataset. If you give a block argument that returns an array with multiple entries, the contents of the resulting array are undefined. Raises an Error if called with both an argument and a block.

DB[:table].select_map(:id) # SELECT id FROM table
# => [3, 5, 8, 1, ...]

DB[:table].select_map{id * 2} # SELECT (id * 2) FROM table
# => [6, 10, 16, 2, ...]

You can also provide an array of column names:

DB[:table].select_map([:id, :name]) # SELECT id, name FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
740 def select_map(column=nil, &block)
741   _select_map(column, false, &block)
742 end
select_order_map(column=nil, &block) click to toggle source

The same as select_map, but in addition orders the array by the column.

DB[:table].select_order_map(:id) # SELECT id FROM table ORDER BY id
# => [1, 2, 3, 4, ...]

DB[:table].select_order_map{id * 2} # SELECT (id * 2) FROM table ORDER BY (id * 2)
# => [2, 4, 6, 8, ...]

You can also provide an array of column names:

DB[:table].select_order_map([:id, :name]) # SELECT id, name FROM table ORDER BY id, name
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
759 def select_order_map(column=nil, &block)
760   _select_map(column, true, &block)
761 end
single_record() click to toggle source

Limits the dataset to one record, and returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method. Example:

DB[:test].single_record # SELECT * FROM test LIMIT 1
# => {:column_name=>'value'}
    # File lib/sequel/dataset/actions.rb
769 def single_record
770   _single_record_ds.single_record!
771 end
single_record!() click to toggle source

Returns the first record in dataset, without limiting the dataset. Returns nil if the dataset has no records. Users should probably use first instead of this method. This should only be used if you know the dataset is already limited to a single record. This method may be desirable to use for performance reasons, as it does not clone the receiver. Example:

DB[:test].single_record! # SELECT * FROM test
# => {:column_name=>'value'}
    # File lib/sequel/dataset/actions.rb
781 def single_record!
782   with_sql_first(select_sql)
783 end
single_value() click to toggle source

Returns the first value of the first record in the dataset. Returns nil if dataset is empty. Users should generally use get instead of this method. Example:

DB[:test].single_value # SELECT * FROM test LIMIT 1
# => 'value'
    # File lib/sequel/dataset/actions.rb
791 def single_value
792   single_value_ds.each do |r|
793     r.each{|_, v| return v}
794   end
795   nil
796 end
single_value!() click to toggle source

Returns the first value of the first record in the dataset, without limiting the dataset. Returns nil if the dataset is empty. Users should generally use get instead of this method. Should not be used on graphed datasets or datasets that have row_procs that don’t return hashes. This method may be desirable to use for performance reasons, as it does not clone the receiver.

DB[:test].single_value! # SELECT * FROM test
# => 'value'
    # File lib/sequel/dataset/actions.rb
806 def single_value!
807   with_sql_single_value(select_sql)
808 end
sum(arg=(no_arg = true), &block) click to toggle source

Returns the sum for the given column/expression. Uses a virtual row block if no column is given.

DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1
# => 55
DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1
# => 10
    # File lib/sequel/dataset/actions.rb
817 def sum(arg=(no_arg = true), &block)
818   arg = Sequel.virtual_row(&block) if no_arg
819   _aggregate(:sum, arg)
820 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

    # File lib/sequel/dataset/actions.rb
874 def to_hash(*a)
875   as_hash(*a)
876 end
to_hash_groups(key_column, value_column = nil, opts = OPTS) click to toggle source

Returns a hash with one column used as key and the values being an array of column values. If the value_column is not given or nil, uses the entire hash as the value.

DB[:table].to_hash_groups(:name, :id) # SELECT * FROM table
# {'Jim'=>[1, 4, 16, ...], 'Bob'=>[2], ...}

DB[:table].to_hash_groups(:name) # SELECT * FROM table
# {'Jim'=>[{:id=>1, :name=>'Jim'}, {:id=>4, :name=>'Jim'}, ...], 'Bob'=>[{:id=>2, :name=>'Bob'}], ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].to_hash_groups([:first, :middle], [:last, :id]) # SELECT * FROM table
# {['Jim', 'Bob']=>[['Smith', 1], ['Jackson', 4], ...], ...}

DB[:table].to_hash_groups([:first, :middle]) # SELECT * FROM table
# {['Jim', 'Bob']=>[{:id=>1, :first=>'Jim', :middle=>'Bob', :last=>'Smith'}, ...], ...}

Options:

:all

Use all instead of each to retrieve the objects

:hash

The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc.

    # File lib/sequel/dataset/actions.rb
902 def to_hash_groups(key_column, value_column = nil, opts = OPTS)
903   h = opts[:hash] || {}
904   meth = opts[:all] ? :all : :each
905   if value_column
906     return naked.to_hash_groups(key_column, value_column, opts) if row_proc
907     if value_column.is_a?(Array)
908       if key_column.is_a?(Array)
909         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
910       else
911         public_send(meth){|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
912       end
913     else
914       if key_column.is_a?(Array)
915         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
916       else
917         public_send(meth){|r| (h[r[key_column]] ||= []) << r[value_column]}
918       end
919     end
920   elsif key_column.is_a?(Array)
921     public_send(meth){|r| (h[key_column.map{|k| r[k]}] ||= []) << r}
922   else
923     public_send(meth){|r| (h[r[key_column]] ||= []) << r}
924   end
925   h
926 end
truncate() click to toggle source

Truncates the dataset. Returns nil.

DB[:table].truncate # TRUNCATE table
# => nil
    # File lib/sequel/dataset/actions.rb
932 def truncate
933   execute_ddl(truncate_sql)
934 end
update(values=OPTS, &block) click to toggle source

Updates values for the dataset. The returned value is the number of rows updated. values should be a hash where the keys are columns to set and values are the values to which to set the columns.

DB[:table].update(x: nil) # UPDATE table SET x = NULL
# => 10

DB[:table].update(x: Sequel[:x]+1, y: 0) # UPDATE table SET x = (x + 1), y = 0
# => 10

Some databases support using multiple tables in an UPDATE query. This requires multiple FROM tables (JOINs can also be used). As multiple FROM tables use an implicit CROSS JOIN, you should make sure your WHERE condition uses the appropriate filters for the FROM tables:

DB.from(:a, :b).join(:c, :d=>Sequel[:b][:e]).where{{a[:f]=>b[:g], a[:id]=>10}}.
  update(:f=>Sequel[:c][:h])
# UPDATE a
# SET f = c.h
# FROM b
# INNER JOIN c ON (c.d = b.e)
# WHERE ((a.f = b.g) AND (a.id = 10))
    # File lib/sequel/dataset/actions.rb
958 def update(values=OPTS, &block)
959   sql = update_sql(values)
960   if uses_returning?(:update)
961     returning_fetch_rows(sql, &block)
962   else
963     execute_dui(sql)
964   end
965 end
where_all(cond, &block) click to toggle source

Return an array of all rows matching the given filter condition, also yielding each row to the given block. Basically the same as where(cond).all(&block), except it can be optimized to not create an intermediate dataset.

DB[:table].where_all(id: [1,2,3])
# SELECT * FROM table WHERE (id IN (1, 2, 3))
    # File lib/sequel/dataset/actions.rb
973 def where_all(cond, &block)
974   if loader = _where_loader([cond], nil)
975     loader.all(filter_expr(cond), &block)
976   else
977     where(cond).all(&block)
978   end
979 end
where_each(cond, &block) click to toggle source

Iterate over all rows matching the given filter condition, yielding each row to the given block. Basically the same as where(cond).each(&block), except it can be optimized to not create an intermediate dataset.

DB[:table].where_each(id: [1,2,3]){|row| p row}
# SELECT * FROM table WHERE (id IN (1, 2, 3))
    # File lib/sequel/dataset/actions.rb
987 def where_each(cond, &block)
988   if loader = _where_loader([cond], nil)
989     loader.each(filter_expr(cond), &block)
990   else
991     where(cond).each(&block)
992   end
993 end
where_single_value(cond) click to toggle source

Filter the datasets using the given filter condition, then return a single value. This assumes that the dataset has already been setup to limit the selection to a single column. Basically the same as where(cond).single_value, except it can be optimized to not create an intermediate dataset.

DB[:table].select(:name).where_single_value(id: 1)
# SELECT name FROM table WHERE (id = 1) LIMIT 1
     # File lib/sequel/dataset/actions.rb
1002 def where_single_value(cond)
1003   if loader = cached_where_placeholder_literalizer([cond], nil, :_where_single_value_loader) do |pl|
1004       single_value_ds.where(pl.arg)
1005     end
1006 
1007     loader.get(filter_expr(cond))
1008   else
1009     where(cond).single_value
1010   end
1011 end
with_sql_all(sql, &block) click to toggle source

Run the given SQL and return an array of all rows. If a block is given, each row is yielded to the block after all rows are loaded. See with_sql_each.

     # File lib/sequel/dataset/actions.rb
1015 def with_sql_all(sql, &block)
1016   _all(block){|a| with_sql_each(sql){|r| a << r}}
1017 end
with_sql_delete(sql) click to toggle source

Execute the given SQL and return the number of rows deleted. This exists solely as an optimization, replacing with_sql(sql).delete. It’s significantly faster as it does not require cloning the current dataset.

     # File lib/sequel/dataset/actions.rb
1022 def with_sql_delete(sql)
1023   execute_dui(sql)
1024 end
Also aliased as: with_sql_update
with_sql_each(sql) { |call| ... } click to toggle source

Run the given SQL and yield each returned row to the block.

     # File lib/sequel/dataset/actions.rb
1028 def with_sql_each(sql)
1029   if rp = row_proc
1030     _with_sql_dataset.fetch_rows(sql){|r| yield rp.call(r)}
1031   else
1032     _with_sql_dataset.fetch_rows(sql){|r| yield r}
1033   end
1034   self
1035 end
with_sql_first(sql) click to toggle source

Run the given SQL and return the first row, or nil if no rows were returned. See with_sql_each.

     # File lib/sequel/dataset/actions.rb
1039 def with_sql_first(sql)
1040   with_sql_each(sql){|r| return r}
1041   nil
1042 end
with_sql_insert(sql) click to toggle source

Execute the given SQL and (on most databases) return the primary key of the inserted row.

     # File lib/sequel/dataset/actions.rb
1055 def with_sql_insert(sql)
1056   execute_insert(sql)
1057 end
with_sql_single_value(sql) click to toggle source

Run the given SQL and return the first value in the first row, or nil if no rows were returned. For this to make sense, the SQL given should select only a single value. See with_sql_each.

     # File lib/sequel/dataset/actions.rb
1047 def with_sql_single_value(sql)
1048   if r = with_sql_first(sql)
1049     r.each{|_, v| return v}
1050   end
1051 end
with_sql_update(sql)
Alias for: with_sql_delete

Protected Instance Methods

_import(columns, values, opts) click to toggle source

Internals of import. If primary key values are requested, use separate insert commands for each row. Otherwise, call multi_insert_sql and execute each statement it gives separately. A transaction is only used if there are multiple statements to execute.

     # File lib/sequel/dataset/actions.rb
1065 def _import(columns, values, opts)
1066   trans_opts = Hash[opts]
1067   trans_opts[:server] = @opts[:server]
1068   if opts[:return] == :primary_key
1069     _import_transaction(values, trans_opts){values.map{|v| insert(columns, v)}}
1070   else
1071     stmts = multi_insert_sql(columns, values)
1072     _import_transaction(stmts, trans_opts){stmts.each{|st| execute_dui(st)}}
1073   end
1074 end
_select_map_multiple(ret_cols) click to toggle source

Return an array of arrays of values given by the symbols in ret_cols.

     # File lib/sequel/dataset/actions.rb
1077 def _select_map_multiple(ret_cols)
1078   map{|r| r.values_at(*ret_cols)}
1079 end
_select_map_single() click to toggle source

Returns an array of the first value in each row.

     # File lib/sequel/dataset/actions.rb
1082 def _select_map_single
1083   k = nil
1084   map{|r| r[k||=r.keys.first]}
1085 end
single_value_ds() click to toggle source

A dataset for returning single values from the current dataset.

     # File lib/sequel/dataset/actions.rb
1088 def single_value_ds
1089   clone(:limit=>1).ungraphed.naked
1090 end

Private Instance Methods

_aggregate(function, arg) click to toggle source

Cached placeholder literalizer for methods that return values using aggregate functions.

     # File lib/sequel/dataset/actions.rb
1104 def _aggregate(function, arg)
1105   if loader = cached_placeholder_literalizer(:"_#{function}_loader") do |pl|
1106         aggregate_dataset.limit(1).select(SQL::Function.new(function, pl.arg).as(function))
1107       end
1108     loader.get(arg)
1109   else
1110     aggregate_dataset.get(SQL::Function.new(function, arg).as(function))
1111   end
1112 end
_all(block) { |a| ... } click to toggle source

Internals of all and with_sql_all

     # File lib/sequel/dataset/actions.rb
1095 def _all(block)
1096   a = []
1097   yield a
1098   post_load(a)
1099   a.each(&block) if block
1100   a
1101 end
_hash_key_symbol(s, recursing=false) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned. Return nil if no hash key can be determined

     # File lib/sequel/dataset/actions.rb
1212 def _hash_key_symbol(s, recursing=false)
1213   case s
1214   when Symbol
1215     _, c, a = split_symbol(s)
1216     (a || c).to_sym
1217   when SQL::Identifier, SQL::Wrapper
1218     _hash_key_symbol(s.value, true)
1219   when SQL::QualifiedIdentifier
1220     _hash_key_symbol(s.column, true)
1221   when SQL::AliasedExpression
1222     _hash_key_symbol(s.alias, true)
1223   when String
1224     s.to_sym if recursing
1225   end
1226 end
_import_transaction(values, trans_opts, &block) click to toggle source

Use a transaction when yielding to the block if multiple values/statements are provided. When only a single value or statement is provided, then yield without using a transaction.

     # File lib/sequel/dataset/actions.rb
1117 def _import_transaction(values, trans_opts, &block)
1118   # OK to mutate trans_opts as it is generated by _import
1119   trans_opts[:skip_transaction] = true if values.length <= 1
1120   @db.transaction(trans_opts, &block)
1121 end
_select_hash(meth, key_column, value_column, opts=OPTS) click to toggle source

Internals of select_hash and select_hash_groups

     # File lib/sequel/dataset/actions.rb
1124 def _select_hash(meth, key_column, value_column, opts=OPTS)
1125   select(*(key_column.is_a?(Array) ? key_column : [key_column]) + (value_column.is_a?(Array) ? value_column : [value_column])).
1126     public_send(meth, hash_key_symbols(key_column), hash_key_symbols(value_column), opts)
1127 end
_select_map(column, order, &block) click to toggle source

Internals of select_map and select_order_map

     # File lib/sequel/dataset/actions.rb
1130 def _select_map(column, order, &block)
1131   ds = ungraphed.naked
1132   columns = Array(column)
1133   virtual_row_columns(columns, block)
1134   select_cols = order ? columns.map{|c| c.is_a?(SQL::OrderedExpression) ? c.expression : c} : columns
1135   ds = ds.order(*columns.map{|c| unaliased_identifier(c)}) if order
1136   if column.is_a?(Array) || (columns.length > 1)
1137     ds.select(*select_cols)._select_map_multiple(hash_key_symbols(select_cols))
1138   else
1139     ds.select(auto_alias_expression(select_cols.first))._select_map_single
1140   end
1141 end
_single_record_ds() click to toggle source

A cached dataset for a single record for this dataset.

     # File lib/sequel/dataset/actions.rb
1144 def _single_record_ds
1145   cached_dataset(:_single_record_ds){clone(:limit=>1)}
1146 end
_where_loader(where_args, where_block) click to toggle source

Loader used for where_all and where_each.

     # File lib/sequel/dataset/actions.rb
1149 def _where_loader(where_args, where_block)
1150   cached_where_placeholder_literalizer(where_args, where_block, :_where_loader) do |pl|
1151     where(pl.arg)
1152   end
1153 end
_with_sql_dataset() click to toggle source

Cached dataset to use for with_sql_#{all,each,first,single_value}. This is used so that the columns returned by the given SQL do not affect the receiver of the with_sql_* method.

     # File lib/sequel/dataset/actions.rb
1330 def _with_sql_dataset
1331   if @opts[:_with_sql_ds]
1332     self
1333   else
1334     cached_dataset(:_with_sql_ds) do
1335       clone(:_with_sql_ds=>true)
1336     end
1337   end
1338 end
auto_alias_expression(v) click to toggle source

Automatically alias the given expression if it does not have an identifiable alias.

     # File lib/sequel/dataset/actions.rb
1156 def auto_alias_expression(v)
1157   case v
1158   when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
1159     v
1160   else
1161     SQL::AliasedExpression.new(v, :v)
1162   end
1163 end
default_import_slice() click to toggle source

The default number of rows that can be inserted in a single INSERT statement via import. The default is for no limit.

     # File lib/sequel/dataset/actions.rb
1167 def default_import_slice
1168   nil
1169 end
default_server_opts(opts) click to toggle source

Set the server to use to :default unless it is already set in the passed opts

     # File lib/sequel/dataset/actions.rb
1172 def default_server_opts(opts)
1173   if @db.sharded? && !opts.has_key?(:server)
1174     opts = Hash[opts]
1175     opts[:server] = @opts[:server] || :default
1176   end
1177   opts
1178 end
execute(sql, opts=OPTS, &block) click to toggle source

Execute the given select SQL on the database using execute. Use the :read_only server unless a specific server is set.

     # File lib/sequel/dataset/actions.rb
1182 def execute(sql, opts=OPTS, &block)
1183   db = @db
1184   if db.sharded? && !opts.has_key?(:server)
1185     opts = Hash[opts]
1186     opts[:server] = @opts[:server] || (@opts[:lock] ? :default : :read_only)
1187     opts
1188   end
1189   db.execute(sql, opts, &block)
1190 end
execute_ddl(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_ddl.

     # File lib/sequel/dataset/actions.rb
1193 def execute_ddl(sql, opts=OPTS, &block)
1194   @db.execute_ddl(sql, default_server_opts(opts), &block)
1195   nil
1196 end
execute_dui(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_dui.

     # File lib/sequel/dataset/actions.rb
1199 def execute_dui(sql, opts=OPTS, &block)
1200   @db.execute_dui(sql, default_server_opts(opts), &block)
1201 end
execute_insert(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_insert.

     # File lib/sequel/dataset/actions.rb
1204 def execute_insert(sql, opts=OPTS, &block)
1205   @db.execute_insert(sql, default_server_opts(opts), &block)
1206 end
hash_key_symbol(s) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned. Raise Error if the hash key symbol cannot be returned.

     # File lib/sequel/dataset/actions.rb
1232 def hash_key_symbol(s)
1233   if v = _hash_key_symbol(s)
1234     v
1235   else
1236     raise(Error, "#{s.inspect} is not supported, should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression")
1237   end
1238 end
hash_key_symbols(s) click to toggle source

If s is an array, return an array with the given hash key symbols. Otherwise, return a hash key symbol for the given expression If a hash key symbol cannot be determined, raise an error.

     # File lib/sequel/dataset/actions.rb
1243 def hash_key_symbols(s)
1244   s.is_a?(Array) ? s.map{|c| hash_key_symbol(c)} : hash_key_symbol(s)
1245 end
ignore_values_preceding(row) { |row, map(&:first)| ... } click to toggle source

Returns an expression that will ignore values preceding the given row, using the receiver’s current order. This yields the row and the array of order expressions to the block, which should return an array of values to use.

     # File lib/sequel/dataset/actions.rb
1250 def ignore_values_preceding(row)
1251   @opts[:order].map{|v| v.is_a?(SQL::OrderedExpression) ? v.expression : v}
1252 
1253   order_exprs = @opts[:order].map do |v|
1254     if v.is_a?(SQL::OrderedExpression)
1255       descending = v.descending
1256       v = v.expression
1257     else
1258       descending = false
1259     end
1260     [v, descending]
1261   end
1262 
1263   row_values = yield(row, order_exprs.map(&:first))
1264 
1265   last_expr = []
1266   cond = order_exprs.zip(row_values).map do |(v, descending), value|
1267     expr =  last_expr + [SQL::BooleanExpression.new(descending ? :< : :>, v, value)]
1268     last_expr += [SQL::BooleanExpression.new(:'=', v, value)]
1269     Sequel.&(*expr)
1270   end
1271   Sequel.|(*cond)
1272 end
output_identifier(v) click to toggle source

Downcase identifiers by default when outputing them from the database.

     # File lib/sequel/dataset/actions.rb
1275 def output_identifier(v)
1276   v = 'untitled' if v == ''
1277   v.to_s.downcase.to_sym
1278 end
post_load(all_records) click to toggle source

This is run inside .all, after all of the records have been loaded via .each, but before any block passed to all is called. It is called with a single argument, an array of all returned records. Does nothing by default, added to make the model eager loading code simpler.

     # File lib/sequel/dataset/actions.rb
1284 def post_load(all_records)
1285 end
returning_fetch_rows(sql, &block) click to toggle source

Called by insert/update/delete when returning is used. Yields each row as a plain hash to the block if one is given, or returns an array of plain hashes for all rows if a block is not given

     # File lib/sequel/dataset/actions.rb
1290 def returning_fetch_rows(sql, &block)
1291   if block
1292     default_server.fetch_rows(sql, &block)
1293     nil
1294   else
1295     rows = []
1296     default_server.fetch_rows(sql){|r| rows << r}
1297     rows
1298   end
1299 end
unaliased_identifier(c) click to toggle source

Return the unaliased part of the identifier. Handles both implicit aliases in symbols, as well as SQL::AliasedExpression objects. Other objects are returned as is.

     # File lib/sequel/dataset/actions.rb
1304 def unaliased_identifier(c)
1305   case c
1306   when Symbol
1307     table, column, aliaz = split_symbol(c)
1308     if aliaz
1309       table ? SQL::QualifiedIdentifier.new(table, column) : Sequel.identifier(column)
1310     else
1311       c
1312     end
1313   when SQL::AliasedExpression
1314     c.expression
1315   when SQL::OrderedExpression
1316     case expr = c.expression
1317     when Symbol, SQL::AliasedExpression
1318       SQL::OrderedExpression.new(unaliased_identifier(expr), c.descending, :nulls=>c.nulls)
1319     else
1320       c
1321     end
1322   else
1323     c
1324   end
1325 end

3 - User Methods relating to SQL Creation

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Public Instance Methods

exists() click to toggle source

Returns an EXISTS clause for the dataset as an SQL::PlaceholderLiteralString.

DB.select(1).where(DB[:items].exists)
# SELECT 1 WHERE (EXISTS (SELECT * FROM items))
   # File lib/sequel/dataset/sql.rb
14 def exists
15   SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
16 end
insert_sql(*values) click to toggle source

Returns an INSERT SQL query string. See insert.

DB[:items].insert_sql(a: 1)
# => "INSERT INTO items (a) VALUES (1)"
   # File lib/sequel/dataset/sql.rb
22 def insert_sql(*values)
23   return static_sql(@opts[:sql]) if @opts[:sql]
24 
25   check_insert_allowed!
26 
27   columns, values = _parse_insert_sql_args(values)
28   if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
29     columns, values = insert_empty_columns_values
30   elsif values.is_a?(Dataset) && hoist_cte?(values) && supports_cte?(:insert)
31     ds, values = hoist_cte(values)
32     return ds.clone(:columns=>columns, :values=>values).send(:_insert_sql)
33   end
34   clone(:columns=>columns, :values=>values).send(:_insert_sql)
35 end
literal_append(sql, v) click to toggle source

Append a literal representation of a value to the given SQL string.

If an unsupported object is given, an Error is raised.

   # File lib/sequel/dataset/sql.rb
40 def literal_append(sql, v)
41   case v
42   when Symbol
43     if skip_symbol_cache?
44       literal_symbol_append(sql, v)
45     else 
46       unless l = db.literal_symbol(v)
47         l = String.new
48         literal_symbol_append(l, v)
49         db.literal_symbol_set(v, l)
50       end
51       sql << l
52     end
53   when String
54     case v
55     when LiteralString
56       sql << v
57     when SQL::Blob
58       literal_blob_append(sql, v)
59     else
60       literal_string_append(sql, v)
61     end
62   when Integer
63     sql << literal_integer(v)
64   when Hash
65     literal_hash_append(sql, v)
66   when SQL::Expression
67     literal_expression_append(sql, v)
68   when Float
69     sql << literal_float(v)
70   when BigDecimal
71     sql << literal_big_decimal(v)
72   when NilClass
73     sql << literal_nil
74   when TrueClass
75     sql << literal_true
76   when FalseClass
77     sql << literal_false
78   when Array
79     literal_array_append(sql, v)
80   when Time
81     v.is_a?(SQLTime) ? literal_sqltime_append(sql, v) : literal_time_append(sql, v)
82   when DateTime
83     literal_datetime_append(sql, v)
84   when Date
85     literal_date_append(sql, v)
86   when Dataset
87     literal_dataset_append(sql, v)
88   else
89     literal_other_append(sql, v)
90   end
91 end
literal_date_or_time(dt, raw=false) click to toggle source

Literalize a date or time value, as a SQL string value with no typecasting. If raw is true, remove the surrounding single quotes. This is designed for usage by bound argument code that can work even if the auto_cast_date_and_time extension is used (either manually or implicitly in the related adapter).

    # File lib/sequel/dataset/sql.rb
123 def literal_date_or_time(dt, raw=false)
124   value = case dt
125   when SQLTime
126     literal_sqltime(dt)
127   when Time
128     literal_time(dt)
129   when DateTime
130     literal_datetime(dt)
131   when Date
132     literal_date(dt)
133   else
134     raise TypeError, "unsupported type: #{dt.inspect}"
135   end
136 
137   if raw
138     value.sub!(/\A'/, '')
139     value.sub!(/'\z/, '')
140   end
141 
142   value
143 end
merge_sql() click to toggle source

The SQL to use for the MERGE statement.

    # File lib/sequel/dataset/sql.rb
 94 def merge_sql
 95   raise Error, "This database doesn't support MERGE" unless supports_merge?
 96   if sql = opts[:sql]
 97     return static_sql(sql)
 98   end
 99   if sql = cache_get(:_merge_sql)
100     return sql
101   end
102   source, join_condition = @opts[:merge_using]
103   raise Error, "No USING clause for MERGE" unless source
104   sql = @opts[:append_sql] || sql_string_origin
105 
106   select_with_sql(sql)
107   sql << "MERGE INTO "
108   source_list_append(sql, @opts[:from])
109   sql << " USING "
110   identifier_append(sql, source)
111   sql << " ON "
112   literal_append(sql, join_condition)
113   _merge_when_sql(sql)
114   cache_set(:_merge_sql, sql) if cache_sql?
115   sql
116 end
multi_insert_sql(columns, values) click to toggle source

Returns an array of insert statements for inserting multiple records. This method is used by multi_insert to format insert statements and expects a keys array and and an array of value arrays.

    # File lib/sequel/dataset/sql.rb
148 def multi_insert_sql(columns, values)
149   case multi_insert_sql_strategy
150   when :values
151     sql = LiteralString.new('VALUES ')
152     expression_list_append(sql, values.map{|r| Array(r)})
153     [insert_sql(columns, sql)]
154   when :union
155     c = false
156     sql = LiteralString.new
157     u = ' UNION ALL SELECT '
158     f = empty_from_sql
159     values.each do |v|
160       if c
161         sql << u
162       else
163         sql << 'SELECT '
164         c = true
165       end
166       expression_list_append(sql, v)
167       sql << f if f
168     end
169     [insert_sql(columns, sql)]
170   else
171     values.map{|r| insert_sql(columns, r)}
172   end
173 end
sql() click to toggle source

Same as select_sql, not aliased directly to make subclassing simpler.

    # File lib/sequel/dataset/sql.rb
176 def sql
177   select_sql
178 end
truncate_sql() click to toggle source

Returns a TRUNCATE SQL query string. See truncate

DB[:items].truncate_sql # => 'TRUNCATE items'
    # File lib/sequel/dataset/sql.rb
183 def truncate_sql
184   if opts[:sql]
185     static_sql(opts[:sql])
186   else
187     check_truncation_allowed!
188     check_not_limited!(:truncate)
189     raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having]
190     t = String.new
191     source_list_append(t, opts[:from])
192     _truncate_sql(t)
193   end
194 end
update_sql(values = OPTS) click to toggle source

Formats an UPDATE statement using the given values. See update.

DB[:items].update_sql(price: 100, category: 'software')
# => "UPDATE items SET price = 100, category = 'software'

Raises an Error if the dataset is grouped or includes more than one table.

    # File lib/sequel/dataset/sql.rb
203 def update_sql(values = OPTS)
204   return static_sql(opts[:sql]) if opts[:sql]
205   check_update_allowed!
206   check_not_limited!(:update)
207 
208   case values
209   when LiteralString
210     # nothing
211   when String
212     raise Error, "plain string passed to Dataset#update is not supported, use Sequel.lit to use a literal string"
213   end
214 
215   clone(:values=>values).send(:_update_sql)
216 end

4 - Methods that describe what the dataset supports

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Public Instance Methods

provides_accurate_rows_matched?() click to toggle source

Whether this dataset will provide accurate number of rows matched for delete and update statements, true by default. Accurate in this case is the number of rows matched by the dataset’s filter.

   # File lib/sequel/dataset/features.rb
19 def provides_accurate_rows_matched?
20   true
21 end
quote_identifiers?() click to toggle source

Whether this dataset quotes identifiers.

   # File lib/sequel/dataset/features.rb
12 def quote_identifiers?
13   @opts.fetch(:quote_identifiers, true)
14 end
recursive_cte_requires_column_aliases?() click to toggle source

Whether you must use a column alias list for recursive CTEs, false by default.

   # File lib/sequel/dataset/features.rb
24 def recursive_cte_requires_column_aliases?
25   false
26 end
requires_placeholder_type_specifiers?() click to toggle source

Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer), false by default.

   # File lib/sequel/dataset/features.rb
41 def requires_placeholder_type_specifiers?
42   false
43 end
requires_sql_standard_datetimes?() click to toggle source

Whether the dataset requires SQL standard datetimes. False by default, as most allow strings with ISO 8601 format. Only for backwards compatibility, no longer used internally, do not use in new code.

   # File lib/sequel/dataset/features.rb
33 def requires_sql_standard_datetimes?
34   # SEQUEL6: Remove
35   false
36 end
supports_cte?(type=:select) click to toggle source

Whether the dataset supports common table expressions, false by default. If given, type can be :select, :insert, :update, or :delete, in which case it determines whether WITH is supported for the respective statement type.

   # File lib/sequel/dataset/features.rb
48 def supports_cte?(type=:select)
49   false
50 end
supports_cte_in_subqueries?() click to toggle source

Whether the dataset supports common table expressions in subqueries, false by default. If false, applies the WITH clause to the main query, which can cause issues if multiple WITH clauses use the same name.

   # File lib/sequel/dataset/features.rb
55 def supports_cte_in_subqueries?
56   false
57 end
supports_deleting_joins?() click to toggle source

Whether deleting from joined datasets is supported, false by default.

   # File lib/sequel/dataset/features.rb
60 def supports_deleting_joins?
61   supports_modifying_joins?
62 end
supports_derived_column_lists?() click to toggle source

Whether the database supports derived column lists (e.g. “table_expr AS table_alias(column_alias1, column_alias2, …)”), true by default.

   # File lib/sequel/dataset/features.rb
67 def supports_derived_column_lists?
68   true
69 end
supports_distinct_on?() click to toggle source

Whether the dataset supports or can emulate the DISTINCT ON clause, false by default.

   # File lib/sequel/dataset/features.rb
72 def supports_distinct_on?
73   false
74 end
supports_group_cube?() click to toggle source

Whether the dataset supports CUBE with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
77 def supports_group_cube?
78   false
79 end
supports_group_rollup?() click to toggle source

Whether the dataset supports ROLLUP with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
82 def supports_group_rollup?
83   false
84 end
supports_grouping_sets?() click to toggle source

Whether the dataset supports GROUPING SETS with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
87 def supports_grouping_sets?
88   false
89 end
supports_insert_select?() click to toggle source

Whether this dataset supports the insert_select method for returning all columns values directly from an insert query, false by default.

   # File lib/sequel/dataset/features.rb
93 def supports_insert_select?
94   supports_returning?(:insert)
95 end
supports_intersect_except?() click to toggle source

Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.

    # File lib/sequel/dataset/features.rb
 98 def supports_intersect_except?
 99   true
100 end
supports_intersect_except_all?() click to toggle source

Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.

    # File lib/sequel/dataset/features.rb
103 def supports_intersect_except_all?
104   true
105 end
supports_is_true?() click to toggle source

Whether the dataset supports the IS TRUE syntax, true by default.

    # File lib/sequel/dataset/features.rb
108 def supports_is_true?
109   true
110 end
supports_join_using?() click to toggle source

Whether the dataset supports the JOIN table USING (column1, …) syntax, true by default. If false, support is emulated using JOIN table ON (table.column1 = other_table.column1).

    # File lib/sequel/dataset/features.rb
114 def supports_join_using?
115   true
116 end
supports_lateral_subqueries?() click to toggle source

Whether the dataset supports LATERAL for subqueries in the FROM or JOIN clauses, false by default.

    # File lib/sequel/dataset/features.rb
119 def supports_lateral_subqueries?
120   false
121 end
supports_limits_in_correlated_subqueries?() click to toggle source

Whether limits are supported in correlated subqueries, true by default.

    # File lib/sequel/dataset/features.rb
124 def supports_limits_in_correlated_subqueries?
125   true
126 end
supports_merge?() click to toggle source

Whether the MERGE statement is supported, false by default.

    # File lib/sequel/dataset/features.rb
134 def supports_merge?
135   false
136 end
supports_modifying_joins?() click to toggle source

Whether modifying joined datasets is supported, false by default.

    # File lib/sequel/dataset/features.rb
139 def supports_modifying_joins?
140   false
141 end
supports_multiple_column_in?() click to toggle source

Whether the IN/NOT IN operators support multiple columns when an array of values is given, true by default.

    # File lib/sequel/dataset/features.rb
145 def supports_multiple_column_in?
146   true
147 end
supports_nowait?() click to toggle source

Whether the dataset supports skipping raising an error instead of waiting for locked rows when returning data, false by default.

    # File lib/sequel/dataset/features.rb
129 def supports_nowait?
130   false
131 end
supports_offsets_in_correlated_subqueries?() click to toggle source

Whether offsets are supported in correlated subqueries, true by default.

    # File lib/sequel/dataset/features.rb
150 def supports_offsets_in_correlated_subqueries?
151   true
152 end
supports_ordered_distinct_on?() click to toggle source

Whether the dataset supports or can fully emulate the DISTINCT ON clause, including respecting the ORDER BY clause, false by default.

    # File lib/sequel/dataset/features.rb
156 def supports_ordered_distinct_on?
157   supports_distinct_on?
158 end
supports_placeholder_literalizer?() click to toggle source

Whether placeholder literalizers are supported, true by default.

    # File lib/sequel/dataset/features.rb
161 def supports_placeholder_literalizer?
162   true
163 end
supports_regexp?() click to toggle source

Whether the dataset supports pattern matching by regular expressions, false by default.

    # File lib/sequel/dataset/features.rb
166 def supports_regexp?
167   false
168 end
supports_replace?() click to toggle source

Whether the dataset supports REPLACE syntax, false by default.

    # File lib/sequel/dataset/features.rb
171 def supports_replace?
172   false
173 end
supports_returning?(type) click to toggle source

Whether the RETURNING clause is supported for the given type of query, false by default. type can be :insert, :update, or :delete.

    # File lib/sequel/dataset/features.rb
177 def supports_returning?(type)
178   false
179 end
supports_select_all_and_column?() click to toggle source

Whether the database supports SELECT *, column FROM table, true by default.

    # File lib/sequel/dataset/features.rb
187 def supports_select_all_and_column?
188   true
189 end
supports_skip_locked?() click to toggle source

Whether the dataset supports skipping locked rows when returning data, false by default.

    # File lib/sequel/dataset/features.rb
182 def supports_skip_locked?
183   false
184 end
supports_timestamp_timezones?() click to toggle source

Whether the dataset supports timezones in literal timestamps, false by default.

    # File lib/sequel/dataset/features.rb
194 def supports_timestamp_timezones?
195   # SEQUEL6: Remove
196   false
197 end
supports_timestamp_usecs?() click to toggle source

Whether the dataset supports fractional seconds in literal timestamps, true by default.

    # File lib/sequel/dataset/features.rb
201 def supports_timestamp_usecs?
202   true
203 end
supports_updating_joins?() click to toggle source

Whether updating joined datasets is supported, false by default.

    # File lib/sequel/dataset/features.rb
206 def supports_updating_joins?
207   supports_modifying_joins?
208 end
supports_where_true?() click to toggle source

Whether the dataset supports WHERE TRUE (or WHERE 1 for databases that that use 1 for true), true by default.

    # File lib/sequel/dataset/features.rb
235 def supports_where_true?
236   true
237 end
supports_window_clause?() click to toggle source

Whether the dataset supports the WINDOW clause to define windows used by multiple window functions, false by default.

    # File lib/sequel/dataset/features.rb
212 def supports_window_clause?
213   false
214 end
supports_window_function_frame_option?(option) click to toggle source

Whether the dataset supports the given window function option. True by default. This should only be called if supports_window_functions? is true. Possible options are :rows, :range, :groups, :offset, :exclude.

    # File lib/sequel/dataset/features.rb
224 def supports_window_function_frame_option?(option)
225   case option
226   when :rows, :range, :offset
227     true
228   else
229     false
230   end
231 end
supports_window_functions?() click to toggle source

Whether the dataset supports window functions, false by default.

    # File lib/sequel/dataset/features.rb
217 def supports_window_functions?
218   false
219 end

Private Instance Methods

insert_supports_empty_values?() click to toggle source

Whether insert(nil) or insert({}) must be emulated by using at least one value.

    # File lib/sequel/dataset/features.rb
243 def insert_supports_empty_values?
244   true
245 end
requires_emulating_nulls_first?() click to toggle source

Whether ORDER BY col NULLS FIRST/LAST must be emulated.

    # File lib/sequel/dataset/features.rb
253 def requires_emulating_nulls_first?
254   false
255 end
requires_like_escape?() click to toggle source

Whether the dataset needs ESCAPE for LIKE for correct behavior.

    # File lib/sequel/dataset/features.rb
248 def requires_like_escape?
249   true
250 end
supports_cte_in_compounds?() click to toggle source

Whether common table expressions are supported in UNION/INTERSECT/EXCEPT clauses.

    # File lib/sequel/dataset/features.rb
258 def supports_cte_in_compounds?
259   supports_cte_in_subqueries?
260 end
supports_filtered_aggregates?() click to toggle source

Whether the dataset supports the FILTER clause for aggregate functions. If not, support is emulated using CASE.

    # File lib/sequel/dataset/features.rb
264 def supports_filtered_aggregates?
265   false
266 end
supports_quoted_function_names?() click to toggle source

Whether the database supports quoting function names.

    # File lib/sequel/dataset/features.rb
269 def supports_quoted_function_names?
270   false
271 end
uses_returning?(type) click to toggle source

Whether the RETURNING clause is used for the given dataset. type can be :insert, :update, or :delete.

    # File lib/sequel/dataset/features.rb
275 def uses_returning?(type)
276   opts[:returning] && !@opts[:sql] && supports_returning?(type)
277 end
uses_with_rollup?() click to toggle source

Whether the dataset uses WITH ROLLUP/CUBE instead of ROLLUP()/CUBE().

    # File lib/sequel/dataset/features.rb
280 def uses_with_rollup?
281   false
282 end

5 - Methods related to dataset graphing

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Public Instance Methods

add_graph_aliases(graph_aliases) click to toggle source

Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list (the equivalent of select_append when graphing). See set_graph_aliases.

DB[:table].add_graph_aliases(some_alias: [:table, :column])
# SELECT ..., table.column AS some_alias
   # File lib/sequel/dataset/graph.rb
18 def add_graph_aliases(graph_aliases)
19   graph = opts[:graph]
20   unless (graph && (ga = graph[:column_aliases]))
21     raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases"
22   end
23   columns, graph_aliases = graph_alias_columns(graph_aliases)
24   select_append(*columns).clone(:graph => graph.merge(:column_aliases=>ga.merge(graph_aliases).freeze).freeze)
25 end
graph(dataset, join_conditions = nil, options = OPTS, &block) click to toggle source

Similar to Dataset#join_table, but uses unambiguous aliases for selected columns and keeps metadata about the aliases for use in other methods.

Arguments:

dataset

Can be a symbol (specifying a table), another dataset, or an SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.

join_conditions

Any condition(s) allowed by join_table.

block

A block that is passed to join_table.

Options:

:from_self_alias

The alias to use when the receiver is not a graphed dataset but it contains multiple FROM tables or a JOIN. In this case, the receiver is wrapped in a from_self before graphing, and this option determines the alias to use.

:implicit_qualifier

The qualifier of implicit conditions, see join_table.

:join_only

Only join the tables, do not change the selected columns.

:join_type

The type of join to use (passed to join_table). Defaults to :left_outer.

:qualify

The type of qualification to do, see join_table.

:select

An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about the join that makes it important to use graph instead of join_table.

:table_alias

The alias to use for the table. If not specified, doesn’t alias the table. You will get an error if the alias (or table) name is used more than once.

    # File lib/sequel/dataset/graph.rb
 53 def graph(dataset, join_conditions = nil, options = OPTS, &block)
 54   # Allow the use of a dataset or symbol as the first argument
 55   # Find the table name/dataset based on the argument
 56   table_alias = options[:table_alias]
 57   table = dataset
 58   create_dataset = true
 59 
 60   case dataset
 61   when Symbol
 62     # let alias be the same as the table name (sans any optional schema)
 63     # unless alias explicitly given in the symbol using ___ notation and symbol splitting is enabled
 64     table_alias ||= split_symbol(table).compact.last
 65   when Dataset
 66     if dataset.simple_select_all?
 67       table = dataset.opts[:from].first
 68       table_alias ||= table
 69     else
 70       table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
 71     end
 72     create_dataset = false
 73   when SQL::Identifier
 74     table_alias ||= table.value
 75   when SQL::QualifiedIdentifier
 76     table_alias ||= split_qualifiers(table).last
 77   when SQL::AliasedExpression
 78     return graph(table.expression, join_conditions, {:table_alias=>table.alias}.merge!(options), &block)
 79   else
 80     raise Error, "The dataset argument should be a symbol or dataset"
 81   end
 82   table_alias = table_alias.to_sym
 83 
 84   if create_dataset
 85     dataset = db.from(table)
 86   end
 87 
 88   # Raise Sequel::Error with explanation that the table alias has been used
 89   raise_alias_error = lambda do
 90     raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \
 91       "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 
 92   end
 93 
 94   # Only allow table aliases that haven't been used
 95   raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
 96   
 97   table_alias_qualifier = qualifier_from_alias_symbol(table_alias, table)
 98   implicit_qualifier = options[:implicit_qualifier]
 99   joined_dataset = joined_dataset?
100   ds = self
101   graph = opts[:graph]
102 
103   if !graph && (select = @opts[:select]) && !select.empty?
104     select_columns = nil
105 
106     unless !joined_dataset && select.length == 1 && (select[0].is_a?(SQL::ColumnAll))
107       force_from_self = false
108       select_columns = select.map do |sel|
109         unless col = _hash_key_symbol(sel)
110           force_from_self = true
111           break
112         end
113 
114         [sel, col]
115       end
116 
117       select_columns = nil if force_from_self
118     end
119   end
120 
121   # Use a from_self if this is already a joined table (or from_self specifically disabled for graphs)
122   if (@opts[:graph_from_self] != false && !graph && (joined_dataset || force_from_self))
123     from_selfed = true
124     implicit_qualifier = options[:from_self_alias] || first_source
125     ds = ds.from_self(:alias=>implicit_qualifier)
126   end
127   
128   # Join the table early in order to avoid cloning the dataset twice
129   ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias_qualifier, :implicit_qualifier=>implicit_qualifier, :qualify=>options[:qualify], &block)
130 
131   return ds if options[:join_only]
132 
133   opts = ds.opts
134 
135   # Whether to include the table in the result set
136   add_table = options[:select] == false ? false : true
137 
138   if graph
139     graph = graph.dup
140     select = opts[:select].dup
141     [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
142   else
143     # Setup the initial graph data structure if it doesn't exist
144     qualifier = ds.first_source_alias
145     master = alias_symbol(qualifier)
146     raise_alias_error.call if master == table_alias
147 
148     # Master hash storing all .graph related information
149     graph = {}
150 
151     # Associates column aliases back to tables and columns
152     column_aliases = graph[:column_aliases] = {}
153 
154     # Associates table alias (the master is never aliased)
155     table_aliases = graph[:table_aliases] = {master=>self}
156 
157     # Keep track of the alias numbers used
158     ca_num = graph[:column_alias_num] = Hash.new(0)
159 
160     select = if select_columns
161       select_columns.map do |sel, column|
162         column_aliases[column] = [master, column]
163         if from_selfed
164           # Initial dataset was wrapped in subselect, selected all
165           # columns in the subselect, qualified by the subselect alias.
166           Sequel.qualify(qualifier, Sequel.identifier(column))
167         else
168           # Initial dataset not wrapped in subslect, just make
169           # sure columns are qualified in some way.
170           qualified_expression(sel, qualifier)
171         end
172       end
173     else
174       columns.map do |column|
175         column_aliases[column] = [master, column]
176         SQL::QualifiedIdentifier.new(qualifier, column)
177       end
178     end
179   end
180 
181   # Add the table alias to the list of aliases
182   # Even if it isn't been used in the result set,
183   # we add a key for it with a nil value so we can check if it
184   # is used more than once
185   table_aliases = graph[:table_aliases]
186   table_aliases[table_alias] = add_table ? dataset : nil
187 
188   # Add the columns to the selection unless we are ignoring them
189   if add_table
190     column_aliases = graph[:column_aliases]
191     ca_num = graph[:column_alias_num]
192     # Which columns to add to the result set
193     cols = options[:select] || dataset.columns
194     # If the column hasn't been used yet, don't alias it.
195     # If it has been used, try table_column.
196     # If that has been used, try table_column_N
197     # using the next value of N that we know hasn't been
198     # used
199     cols.each do |column|
200       col_alias, identifier = if column_aliases[column]
201         column_alias = :"#{table_alias}_#{column}"
202         if column_aliases[column_alias]
203           column_alias_num = ca_num[column_alias]
204           column_alias = :"#{column_alias}_#{column_alias_num}" 
205           ca_num[column_alias] += 1
206         end
207         [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias_qualifier, column), column_alias)]
208       else
209         ident = SQL::QualifiedIdentifier.new(table_alias_qualifier, column)
210         [column, ident]
211       end
212       column_aliases[col_alias] = [table_alias, column].freeze
213       select.push(identifier)
214     end
215   end
216   [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k].freeze}
217   ds = ds.clone(:graph=>graph.freeze)
218   ds.select(*select)
219 end
set_graph_aliases(graph_aliases) click to toggle source

This allows you to manually specify the graph aliases to use when using graph. You can use it to only select certain columns, and have those columns mapped to specific aliases in the result set. This is the equivalent of select for a graphed dataset, and must be used instead of select whenever graphing is used.

graph_aliases should be a hash with keys being symbols of column aliases, and values being either symbols or arrays with one to three elements. If the value is a symbol, it is assumed to be the same as a one element array containing that symbol. The first element of the array should be the table alias symbol. The second should be the actual column name symbol. If the array only has a single element the column name symbol will be assumed to be the same as the corresponding hash key. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.

DB[:artists].graph(:albums, :artist_id: :id).
  set_graph_aliases(name: :artists,
                    album_name: [:albums, :name],
                    forty_two: [:albums, :fourtwo, 42]).first
# SELECT artists.name, albums.name AS album_name, 42 AS forty_two ...
    # File lib/sequel/dataset/graph.rb
244 def set_graph_aliases(graph_aliases)
245   columns, graph_aliases = graph_alias_columns(graph_aliases)
246   if graph = opts[:graph]
247     select(*columns).clone(:graph => graph.merge(:column_aliases=>graph_aliases.freeze).freeze)
248   else
249     raise Error, "cannot call #set_graph_aliases on an ungraphed dataset"
250   end
251 end
ungraphed() click to toggle source

Remove the splitting of results into subhashes, and all metadata related to the current graph (if any).

    # File lib/sequel/dataset/graph.rb
255 def ungraphed
256   return self unless opts[:graph]
257   clone(:graph=>nil)
258 end

Private Instance Methods

graph_alias_columns(graph_aliases) click to toggle source

Transform the hash of graph aliases and return a two element array where the first element is an array of identifiers suitable to pass to a select method, and the second is a new hash of preprocessed graph aliases.

    # File lib/sequel/dataset/graph.rb
284 def graph_alias_columns(graph_aliases)
285   gas = {}
286   identifiers = graph_aliases.map do |col_alias, tc| 
287     table, column, value = Array(tc)
288     column ||= col_alias
289     gas[col_alias] = [table, column].freeze
290     identifier = value || SQL::QualifiedIdentifier.new(table, column)
291     identifier = SQL::AliasedExpression.new(identifier, col_alias) if value || column != col_alias
292     identifier
293   end
294   [identifiers, gas]
295 end
qualifier_from_alias_symbol(aliaz, identifier) click to toggle source

Wrap the alias symbol in an SQL::Identifier if the identifier on which is based is an SQL::Identifier. This works around cases where symbol splitting is enabled and the alias symbol contains double embedded underscores which would be considered an implicit qualified identifier if not wrapped in an SQL::Identifier.

    # File lib/sequel/dataset/graph.rb
266 def qualifier_from_alias_symbol(aliaz, identifier)
267   case identifier
268   when SQL::QualifiedIdentifier
269     if identifier.column.is_a?(String)
270       Sequel.identifier(aliaz)
271     else
272       aliaz
273     end
274   when SQL::Identifier
275     Sequel.identifier(aliaz)
276   else
277     aliaz
278   end
279 end

6 - Miscellaneous methods

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Attributes

cache[R]

Access the cache for the current dataset. Should be used with caution, as access to the cache is not thread safe without a mutex if other threads can reference the dataset. Symbol keys prefixed with an underscore are reserved for internal use.

db[R]

The database related to this dataset. This is the Database instance that will execute all of this dataset’s queries.

opts[R]

The hash of options for this dataset, keys are symbols.

Public Class Methods

new(db) click to toggle source

Constructs a new Dataset instance with an associated database and options. Datasets are usually constructed by invoking the Database#[] method:

DB[:posts]

Sequel::Dataset is an abstract class that is not useful by itself. Each database adapter provides a subclass of Sequel::Dataset, and has the Database#dataset method return an instance of that subclass.

   # File lib/sequel/dataset/misc.rb
25 def initialize(db)
26   @db = db
27   @opts = OPTS
28   @cache = {}
29   freeze
30 end

Public Instance Methods

==(o) click to toggle source

Define a hash value such that datasets with the same class, DB, and opts will be considered equal.

   # File lib/sequel/dataset/misc.rb
34 def ==(o)
35   o.is_a?(self.class) && db == o.db && opts == o.opts
36 end
current_datetime() click to toggle source

An object representing the current date or time, should be an instance of Sequel.datetime_class.

   # File lib/sequel/dataset/misc.rb
40 def current_datetime
41   Sequel.datetime_class.now
42 end
dup() click to toggle source

Return self, as datasets are always frozen.

   # File lib/sequel/dataset/misc.rb
50 def dup
51   self
52 end
each_server() { |server(s)| ... } click to toggle source

Yield a dataset for each server in the connection pool that is tied to that server. Intended for use in sharded environments where all servers need to be modified with the same data:

DB[:configs].where(key: 'setting').each_server{|ds| ds.update(value: 'new_value')}
   # File lib/sequel/dataset/misc.rb
59 def each_server
60   db.servers.each{|s| yield server(s)}
61 end
eql?(o) click to toggle source

Alias for ==

   # File lib/sequel/dataset/misc.rb
45 def eql?(o)
46   self == o
47 end
escape_like(string) click to toggle source

Returns the string with the LIKE metacharacters (% and _) escaped. Useful for when the LIKE term is a user-provided string where metacharacters should not be recognized. Example:

ds.escape_like("foo\\%_") # 'foo\\\%\_'
   # File lib/sequel/dataset/misc.rb
68 def escape_like(string)
69   string.gsub(/[\\%_]/){|m| "\\#{m}"}
70 end
first_source() click to toggle source

Alias of first_source_alias

   # File lib/sequel/dataset/misc.rb
91 def first_source
92   first_source_alias
93 end
first_source_alias() click to toggle source

The first source (primary table) for this dataset. If the dataset doesn’t have a table, raises an Error. If the table is aliased, returns the aliased name.

DB[:table].first_source_alias
# => :table

DB[Sequel[:table].as(:t)].first_source_alias
# => :t
    # File lib/sequel/dataset/misc.rb
103 def first_source_alias
104   source = @opts[:from]
105   if source.nil? || source.empty?
106     raise Error, 'No source specified for query'
107   end
108   case s = source.first
109   when SQL::AliasedExpression
110     s.alias
111   when Symbol
112     _, _, aliaz = split_symbol(s)
113     aliaz ? aliaz.to_sym : s
114   else
115     s
116   end
117 end
first_source_table() click to toggle source

The first source (primary table) for this dataset. If the dataset doesn’t have a table, raises an error. If the table is aliased, returns the original table, not the alias

DB[:table].first_source_table
# => :table

DB[Sequel[:table].as(:t)].first_source_table
# => :table
    # File lib/sequel/dataset/misc.rb
128 def first_source_table
129   source = @opts[:from]
130   if source.nil? || source.empty?
131     raise Error, 'No source specified for query'
132   end
133   case s = source.first
134   when SQL::AliasedExpression
135     s.expression
136   when Symbol
137     sch, table, aliaz = split_symbol(s)
138     aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
139   else
140     s
141   end
142 end
freeze() click to toggle source

Freeze the opts when freezing the dataset.

Calls superclass method
   # File lib/sequel/dataset/misc.rb
74 def freeze
75   @opts.freeze
76   super
77 end
hash() click to toggle source

Define a hash value such that datasets with the same class, DB, and opts, will have the same hash value.

    # File lib/sequel/dataset/misc.rb
146 def hash
147   [self.class, db, opts].hash
148 end
inspect() click to toggle source

Returns a string representation of the dataset including the class name and the corresponding SQL select statement.

    # File lib/sequel/dataset/misc.rb
152 def inspect
153   "#<#{visible_class_name}: #{sql.inspect}>"
154 end
joined_dataset?() click to toggle source

Whether this dataset is a joined dataset (multiple FROM tables or any JOINs).

    # File lib/sequel/dataset/misc.rb
157 def joined_dataset?
158  !!((opts[:from].is_a?(Array) && opts[:from].size > 1) || opts[:join])
159 end
placeholder_literalizer_class() click to toggle source

The class to use for placeholder literalizers for the current dataset.

    # File lib/sequel/dataset/misc.rb
162 def placeholder_literalizer_class
163   ::Sequel::Dataset::PlaceholderLiteralizer
164 end
placeholder_literalizer_loader(&block) click to toggle source

A placeholder literalizer loader for the current dataset.

    # File lib/sequel/dataset/misc.rb
167 def placeholder_literalizer_loader(&block)
168   placeholder_literalizer_class.loader(self, &block)
169 end
row_number_column() click to toggle source

The alias to use for the row_number column, used when emulating OFFSET support and for eager limit strategies

    # File lib/sequel/dataset/misc.rb
173 def row_number_column
174   :x_sequel_row_number_x
175 end
row_proc() click to toggle source

The row_proc for this database, should be any object that responds to call with a single hash argument and returns the object you want each to return.

    # File lib/sequel/dataset/misc.rb
179 def row_proc
180   @opts[:row_proc]
181 end
split_alias(c) click to toggle source

Splits a possible implicit alias in c, handling both SQL::AliasedExpressions and Symbols. Returns an array of two elements, with the first being the main expression, and the second being the alias.

    # File lib/sequel/dataset/misc.rb
186 def split_alias(c)
187   case c
188   when Symbol
189     c_table, column, aliaz = split_symbol(c)
190     [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
191   when SQL::AliasedExpression
192     [c.expression, c.alias]
193   when SQL::JoinClause
194     [c.table, c.table_alias]
195   else
196     [c, nil]
197   end
198 end
unqualified_column_for(v) click to toggle source

This returns an SQL::Identifier or SQL::AliasedExpression containing an SQL identifier that represents the unqualified column for the given value. The given value should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression containing one of those. In other cases, this returns nil.

    # File lib/sequel/dataset/misc.rb
205 def unqualified_column_for(v)
206   unless v.is_a?(String)
207     _unqualified_column_for(v)
208   end
209 end
unused_table_alias(table_alias, used_aliases = []) click to toggle source

Creates a unique table alias that hasn’t already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with “_N” if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.

You can provide a second addition array argument containing symbols that should not be considered valid table aliases. The current aliases for the FROM and JOIN tables are automatically included in this array.

DB[:table].unused_table_alias(:t)
# => :t

DB[:table].unused_table_alias(:table)
# => :table_0

DB[:table, :table_0].unused_table_alias(:table)
# => :table_1

DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2])
# => :table_3
    # File lib/sequel/dataset/misc.rb
233 def unused_table_alias(table_alias, used_aliases = [])
234   table_alias = alias_symbol(table_alias)
235   used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
236   used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
237   if used_aliases.include?(table_alias)
238     i = 0
239     while true
240       ta = :"#{table_alias}_#{i}"
241       return ta unless used_aliases.include?(ta)
242       i += 1 
243     end
244   else
245     table_alias
246   end
247 end
with_quote_identifiers(v) click to toggle source

Return a modified dataset with quote_identifiers set.

    # File lib/sequel/dataset/misc.rb
250 def with_quote_identifiers(v)
251   clone(:quote_identifiers=>v, :skip_symbol_cache=>true)
252 end

Protected Instance Methods

_columns() click to toggle source

The cached columns for the current dataset.

    # File lib/sequel/dataset/misc.rb
281 def _columns
282   cache_get(:_columns)
283 end
cache_get(k) click to toggle source

Retreive a value from the dataset’s cache in a thread safe manner.

    # File lib/sequel/dataset/misc.rb
263 def cache_get(k)
264   Sequel.synchronize{@cache[k]}
265 end
cache_set(k, v) click to toggle source

Set a value in the dataset’s cache in a thread safe manner.

    # File lib/sequel/dataset/misc.rb
268 def cache_set(k, v)
269   Sequel.synchronize{@cache[k] = v}
270 end
clear_columns_cache() click to toggle source

Clear the columns hash for the current dataset. This is not a thread safe operation, so it should only be used if the dataset could not be used by another thread (such as one that was just created via clone).

    # File lib/sequel/dataset/misc.rb
276 def clear_columns_cache
277   @cache.delete(:_columns)
278 end

Private Instance Methods

_unqualified_column_for(v) click to toggle source

Internal recursive version of unqualified_column_for, handling Strings inside of other objects.

    # File lib/sequel/dataset/misc.rb
355 def _unqualified_column_for(v)
356   case v
357   when Symbol
358     _, c, a = Sequel.split_symbol(v)
359     c = Sequel.identifier(c)
360     a ? c.as(a) : c
361   when String
362     Sequel.identifier(v)
363   when SQL::Identifier
364     v
365   when SQL::QualifiedIdentifier
366     _unqualified_column_for(v.column)
367   when SQL::AliasedExpression
368     if expr = unqualified_column_for(v.expression)
369       SQL::AliasedExpression.new(expr, v.alias)
370     end
371   end
372 end
cached_dataset(key) { || ... } click to toggle source

Check the cache for the given key, returning the value. Otherwise, yield to get the dataset and cache the dataset under the given key.

    # File lib/sequel/dataset/misc.rb
289 def cached_dataset(key)
290   unless ds = cache_get(key)
291     ds = yield
292     cache_set(key, ds)
293   end
294 
295   ds
296 end
cached_placeholder_literalizer(key) { |pl| ... } click to toggle source

Return a cached placeholder literalizer for the given key if there is one for this dataset. If there isn’t one, increment the counter for the number of calls for the key, and if the counter is at least three, then create a placeholder literalizer by yielding to the block, and cache it.

    # File lib/sequel/dataset/misc.rb
303 def cached_placeholder_literalizer(key)
304   if loader = cache_get(key)
305     return loader unless loader.is_a?(Integer)
306     loader += 1
307 
308     if loader >= 3
309       loader = placeholder_literalizer_loader{|pl, _| yield pl}
310       cache_set(key, loader)
311     else
312       cache_set(key, loader + 1)
313       loader = nil
314     end
315   elsif cache_sql? && supports_placeholder_literalizer?
316     cache_set(key, 1)
317   end
318 
319   loader
320 end
cached_where_placeholder_literalizer(where_args, where_block, key, &block) click to toggle source

Return a cached placeholder literalizer for the key, unless where_block is nil and where_args is an empty array or hash. This is designed to guard against placeholder literalizer use when passing arguments to where in the uncached case and filter_expr if a cached placeholder literalizer is used.

    # File lib/sequel/dataset/misc.rb
327 def cached_where_placeholder_literalizer(where_args, where_block, key, &block)
328   where_args = where_args[0] if where_args.length == 1
329   unless where_block
330     return if where_args == OPTS || where_args == EMPTY_ARRAY
331   end
332 
333   cached_placeholder_literalizer(key, &block)
334 end
columns=(v) click to toggle source

Set the columns for the current dataset.

    # File lib/sequel/dataset/misc.rb
337 def columns=(v)
338   cache_set(:_columns, v)
339 end
initialize_clone(c, _=nil) click to toggle source

Set the db, opts, and cache for the copy of the dataset.

    # File lib/sequel/dataset/misc.rb
342 def initialize_clone(c, _=nil)
343   @db = c.db
344   @opts = Hash[c.opts]
345   if cols = c.cache_get(:_columns)
346     @cache = {:_columns=>cols}
347   else
348     @cache = {}
349   end
350 end
Also aliased as: initialize_copy
initialize_copy(c, _=nil)
Alias for: initialize_clone
visible_class_name() click to toggle source

Return the class name for this dataset, but skip anonymous classes

    # File lib/sequel/dataset/misc.rb
375 def visible_class_name
376   c = self.class
377   c = c.superclass while c.name.nil? || c.name == ''
378   c.name
379 end

8 - Methods related to prepared statements or bound variables

↑ top

Constants

DEFAULT_PREPARED_STATEMENT_MODULE_METHODS
PREPARED_ARG_PLACEHOLDER
PREPARED_STATEMENT_MODULE_CODE

Private Class Methods

prepared_statements_module(code, mods, meths=DEFAULT_PREPARED_STATEMENT_MODULE_METHODS, &block) click to toggle source
   # File lib/sequel/dataset/prepared_statements.rb
20 def self.prepared_statements_module(code, mods, meths=DEFAULT_PREPARED_STATEMENT_MODULE_METHODS, &block)
21   code = PREPARED_STATEMENT_MODULE_CODE[code] || code
22 
23   Module.new do
24     Array(mods).each do |mod|
25       include mod
26     end
27 
28     if block
29       module_eval(&block)
30     end
31 
32     meths.each do |meth|
33       module_eval("def #{meth}(sql, opts=Sequel::OPTS) #{code}; super end", __FILE__, __LINE__)
34     end
35     private(*meths)
36   end
37 end

Public Instance Methods

bind(bind_vars=OPTS) click to toggle source

Set the bind variables to use for the call. If bind variables have already been set for this dataset, they are updated with the contents of bind_vars.

DB[:table].where(id: :$id).bind(id: 1).call(:first)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
    # File lib/sequel/dataset/prepared_statements.rb
332 def bind(bind_vars=OPTS)
333   bind_vars = if bv = @opts[:bind_vars]
334     bv.merge(bind_vars).freeze
335   else
336     if bind_vars.frozen?
337       bind_vars
338     else
339       Hash[bind_vars]
340     end
341   end
342 
343   clone(:bind_vars=>bind_vars)
344 end
call(type, bind_variables=OPTS, *values, &block) click to toggle source

For the given type (:select, :first, :insert, :insert_select, :update, :delete, or :single_value), run the sql with the bind variables specified in the hash. values is a hash passed to insert or update (if one of those types is used), which may contain placeholders.

DB[:table].where(id: :$id).call(:first, id: 1)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
    # File lib/sequel/dataset/prepared_statements.rb
353 def call(type, bind_variables=OPTS, *values, &block)
354   to_prepared_statement(type, values, :extend=>bound_variable_modules).call(bind_variables, &block)
355 end
prepare(type, name, *values) click to toggle source

Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement.

This returns a clone of the dataset extended with PreparedStatementMethods, which you can call with the hash of bind variables to use. The prepared statement is also stored in the associated Database, where it can be called by name. The following usage is identical:

ps = DB[:table].where(name: :$name).prepare(:first, :select_by_name)

ps.call(name: 'Blah')
# SELECT * FROM table WHERE name = ? -- ('Blah')
# => {:id=>1, :name=>'Blah'}

DB.call(:select_by_name, name: 'Blah') # Same thing
    # File lib/sequel/dataset/prepared_statements.rb
373 def prepare(type, name, *values)
374   ps = to_prepared_statement(type, values, :name=>name, :extend=>prepared_statement_modules, :no_delayed_evaluations=>true)
375 
376   ps = if ps.send(:emulate_prepared_statements?)
377     ps = ps.with_extend(EmulatePreparedStatementMethods)
378     ps.send(:emulated_prepared_statement, type, name, values)
379   else
380     sql = ps.prepared_sql
381     ps.prepared_args.freeze
382     ps.clone(:prepared_sql=>sql, :sql=>sql)
383   end
384 
385   db.set_prepared_statement(name, ps)
386   ps
387 end

Protected Instance Methods

to_prepared_statement(type, values=nil, opts=OPTS) click to toggle source

Return a cloned copy of the current dataset extended with PreparedStatementMethods, setting the type and modify values.

    # File lib/sequel/dataset/prepared_statements.rb
393 def to_prepared_statement(type, values=nil, opts=OPTS)
394   mods = opts[:extend] || []
395   mods += [PreparedStatementMethods]
396 
397   bind.
398     clone(:prepared_statement_name=>opts[:name], :prepared_type=>type, :prepared_modify_values=>values, :orig_dataset=>self, :no_cache_sql=>true, :prepared_args=>@opts[:prepared_args]||[], :no_delayed_evaluations=>opts[:no_delayed_evaluations]).
399     with_extend(*mods)
400 end

Private Instance Methods

allow_preparing_prepared_statements?() click to toggle source

Don’t allow preparing prepared statements by default.

    # File lib/sequel/dataset/prepared_statements.rb
405 def allow_preparing_prepared_statements?
406   false
407 end
bound_variable_modules() click to toggle source
    # File lib/sequel/dataset/prepared_statements.rb
409 def bound_variable_modules
410   prepared_statement_modules
411 end
emulate_prepared_statements?() click to toggle source

Whether prepared statements should be emulated. True by default so that adapters have to opt in.

    # File lib/sequel/dataset/prepared_statements.rb
415 def emulate_prepared_statements?
416   true
417 end
prepared_arg_placeholder() click to toggle source

The argument placeholder. Most databases used unnumbered arguments with question marks, so that is the default.

    # File lib/sequel/dataset/prepared_statements.rb
425 def prepared_arg_placeholder
426   PREPARED_ARG_PLACEHOLDER
427 end
prepared_statement_modules() click to toggle source
    # File lib/sequel/dataset/prepared_statements.rb
419 def prepared_statement_modules
420   []
421 end

9 - Internal Methods relating to SQL Creation

↑ top

Constants

BITWISE_METHOD_MAP
COUNT_FROM_SELF_OPTS
COUNT_OF_ALL_AS_COUNT
DEFAULT
EXISTS
IS_LITERALS
IS_OPERATORS
LIKE_OPERATORS
MERGE_NORMALIZE_TYPE_MAP
MERGE_TYPE_SQL

Mapping of merge types to related SQL

N_ARITY_OPERATORS
QUALIFY_KEYS
REGEXP_OPERATORS
TWO_ARITY_OPERATORS
WILDCARD

Public Class Methods

clause_methods(type, clauses) click to toggle source

Given a type (e.g. select) and an array of clauses, return an array of methods to call to build the SQL string.

    # File lib/sequel/dataset/sql.rb
225 def self.clause_methods(type, clauses)
226   clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze
227 end
def_sql_method(mod, type, clauses) click to toggle source

Define a dataset literalization method for the given type in the given module, using the given clauses.

Arguments:

mod

Module in which to define method

type

Type of SQL literalization method to create, either :select, :insert, :update, or :delete

clauses

array of clauses that make up the SQL query for the type. This can either be a single array of symbols/strings, or it can be an array of pairs, with the first element in each pair being an if/elsif/else code fragment, and the second element in each pair being an array of symbol/strings for the appropriate branch.

    # File lib/sequel/dataset/sql.rb
239 def self.def_sql_method(mod, type, clauses)
240   priv = type == :update || type == :insert
241   cacheable = type == :select || type == :delete
242 
243   lines = []
244   lines << 'private' if priv
245   lines << "def #{'_' if priv}#{type}_sql"
246   lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv
247   lines << "if sql = cache_get(:_#{type}_sql); return sql end" if cacheable
248   lines << 'check_delete_allowed!' << 'check_not_limited!(:delete)' if type == :delete
249   lines << 'sql = @opts[:append_sql] || sql_string_origin'
250 
251   if clauses.all?{|c| c.is_a?(Array)}
252     clauses.each do |i, cs|
253       lines << i
254       lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"}) 
255     end 
256     lines << 'end'
257   else
258     lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"})
259   end
260 
261   lines << "cache_set(:_#{type}_sql, sql) if cache_sql?" if cacheable
262   lines << 'sql'
263   lines << 'end'
264 
265   mod.class_eval lines.join("\n"), __FILE__, __LINE__
266 end

Public Instance Methods

aliased_expression_sql_append(sql, ae) click to toggle source

Append literalization of aliased expression to SQL string.

    # File lib/sequel/dataset/sql.rb
300 def aliased_expression_sql_append(sql, ae)
301   literal_append(sql, ae.expression)
302   as_sql_append(sql, ae.alias, ae.columns)
303 end
array_sql_append(sql, a) click to toggle source

Append literalization of array to SQL string.

    # File lib/sequel/dataset/sql.rb
306 def array_sql_append(sql, a)
307   if a.empty?
308     sql << '(NULL)'
309   else
310     sql << '('
311     expression_list_append(sql, a)
312     sql << ')'
313   end
314 end
boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb
317 def boolean_constant_sql_append(sql, constant)
318   if (constant == true || constant == false) && !supports_where_true?
319     sql << (constant == true ? '(1 = 1)' : '(1 = 0)')
320   else
321     literal_append(sql, constant)
322   end
323 end
case_expression_sql_append(sql, ce) click to toggle source

Append literalization of case expression to SQL string.

    # File lib/sequel/dataset/sql.rb
326 def case_expression_sql_append(sql, ce)
327   sql << '(CASE'
328   if ce.expression?
329     sql << ' '
330     literal_append(sql, ce.expression)
331   end
332   w = " WHEN "
333   t = " THEN "
334   ce.conditions.each do |c,r|
335     sql << w
336     literal_append(sql, c)
337     sql << t
338     literal_append(sql, r)
339   end
340   sql << " ELSE "
341   literal_append(sql, ce.default)
342   sql << " END)"
343 end
cast_sql_append(sql, expr, type) click to toggle source

Append literalization of cast expression to SQL string.

    # File lib/sequel/dataset/sql.rb
346 def cast_sql_append(sql, expr, type)
347   sql << 'CAST('
348   literal_append(sql, expr)
349   sql << ' AS ' << db.cast_type_literal(type).to_s
350   sql << ')'
351 end
column_all_sql_append(sql, ca) click to toggle source

Append literalization of column all selection to SQL string.

    # File lib/sequel/dataset/sql.rb
354 def column_all_sql_append(sql, ca)
355   qualified_identifier_sql_append(sql, ca.table, WILDCARD)
356 end
complex_expression_sql_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string.

    # File lib/sequel/dataset/sql.rb
359 def complex_expression_sql_append(sql, op, args)
360   case op
361   when *IS_OPERATORS
362     r = args[1]
363     if r.nil? || supports_is_true?
364       raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r]
365       sql << '('
366       literal_append(sql, args[0])
367       sql << ' ' << op.to_s << ' '
368       sql << val << ')'
369     elsif op == :IS
370       complex_expression_sql_append(sql, :"=", args)
371     else
372       complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args[0], nil)])
373     end
374   when :IN, :"NOT IN"
375     cols = args[0]
376     vals = args[1]
377     col_array = true if cols.is_a?(Array)
378     if vals.is_a?(Array)
379       val_array = true
380       empty_val_array = vals == []
381     end
382     if empty_val_array
383       literal_append(sql, empty_array_value(op, cols))
384     elsif col_array
385       if !supports_multiple_column_in?
386         if val_array
387           expr = SQL::BooleanExpression.new(:OR, *vals.to_a.map{|vs| SQL::BooleanExpression.from_value_pairs(cols.to_a.zip(vs).map{|c, v| [c, v]})})
388           literal_append(sql, op == :IN ? expr : ~expr)
389         else
390           old_vals = vals
391           vals = vals.naked if vals.is_a?(Sequel::Dataset)
392           vals = vals.to_a
393           val_cols = old_vals.columns
394           complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
395         end
396       else
397         # If the columns and values are both arrays, use array_sql instead of
398         # literal so that if values is an array of two element arrays, it
399         # will be treated as a value list instead of a condition specifier.
400         sql << '('
401         literal_append(sql, cols)
402         sql << ' ' << op.to_s << ' '
403         if val_array
404           array_sql_append(sql, vals)
405         else
406           literal_append(sql, vals)
407         end
408         sql << ')'
409       end
410     else
411       sql << '('
412       literal_append(sql, cols)
413       sql << ' ' << op.to_s << ' '
414       literal_append(sql, vals)
415       sql << ')'
416     end
417   when :LIKE, :'NOT LIKE'
418     sql << '('
419     literal_append(sql, args[0])
420     sql << ' ' << op.to_s << ' '
421     literal_append(sql, args[1])
422     if requires_like_escape?
423       sql << " ESCAPE "
424       literal_append(sql, "\\")
425     end
426     sql << ')'
427   when :ILIKE, :'NOT ILIKE'
428     complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : :"NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)})
429   when :**
430     function_sql_append(sql, Sequel.function(:power, *args))
431   when *TWO_ARITY_OPERATORS
432     if REGEXP_OPERATORS.include?(op) && !supports_regexp?
433       raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}"
434     end
435     sql << '('
436     literal_append(sql, args[0])
437     sql << ' ' << op.to_s << ' '
438     literal_append(sql, args[1])
439     sql << ')'
440   when *N_ARITY_OPERATORS
441     sql << '('
442     c = false
443     op_str = " #{op} "
444     args.each do |a|
445       sql << op_str if c
446       literal_append(sql, a)
447       c ||= true
448     end
449     sql << ')'
450   when :NOT
451     sql << 'NOT '
452     literal_append(sql, args[0])
453   when :NOOP
454     literal_append(sql, args[0])
455   when :'B~'
456     sql << '~'
457     literal_append(sql, args[0])
458   when :extract
459     sql << 'extract(' << args[0].to_s << ' FROM '
460     literal_append(sql, args[1])
461     sql << ')'
462   else
463     raise(InvalidOperation, "invalid operator #{op}")
464   end
465 end
constant_sql_append(sql, constant) click to toggle source

Append literalization of constant to SQL string.

    # File lib/sequel/dataset/sql.rb
468 def constant_sql_append(sql, constant)
469   sql << constant.to_s
470 end
delayed_evaluation_sql_append(sql, delay) click to toggle source

Append literalization of delayed evaluation to SQL string, causing the delayed evaluation proc to be evaluated.

    # File lib/sequel/dataset/sql.rb
474 def delayed_evaluation_sql_append(sql, delay)
475   # Delayed evaluations are used specifically so the SQL
476   # can differ in subsequent calls, so we definitely don't
477   # want to cache the sql in this case.
478   disable_sql_caching!
479 
480   if recorder = @opts[:placeholder_literalizer]
481     recorder.use(sql, lambda{delay.call(self)}, nil)
482   else
483     literal_append(sql, delay.call(self))
484   end
485 end
function_sql_append(sql, f) click to toggle source

Append literalization of function call to SQL string.

    # File lib/sequel/dataset/sql.rb
488 def function_sql_append(sql, f)
489   name = f.name
490   opts = f.opts
491 
492   if opts[:emulate]
493     if emulate_function?(name)
494       emulate_function_sql_append(sql, f)
495       return
496     end
497 
498     name = native_function_name(name) 
499   end
500 
501   sql << 'LATERAL ' if opts[:lateral]
502 
503   case name
504   when SQL::Identifier
505     if supports_quoted_function_names? && opts[:quoted]
506       literal_append(sql, name)
507     else
508       sql << name.value.to_s
509     end
510   when SQL::QualifiedIdentifier
511     if supports_quoted_function_names? && opts[:quoted] != false
512       literal_append(sql, name)
513     else
514       sql << split_qualifiers(name).join('.')
515     end
516   else
517     if supports_quoted_function_names? && opts[:quoted]
518       quote_identifier_append(sql, name)
519     else
520       sql << name.to_s
521     end
522   end
523 
524   sql << '('
525   if filter = opts[:filter]
526     filter = filter_expr(filter, &opts[:filter_block])
527   end
528   if opts[:*]
529     if filter && !supports_filtered_aggregates?
530       literal_append(sql, Sequel.case({filter=>1}, nil))
531       filter = nil
532     else
533       sql <<  '*'
534     end
535   else
536     sql << "DISTINCT " if opts[:distinct]
537     if filter && !supports_filtered_aggregates?
538       expression_list_append(sql, f.args.map{|arg| Sequel.case({filter=>arg}, nil)})
539       filter = nil
540     else
541       expression_list_append(sql, f.args)
542     end
543     if order = opts[:order]
544       sql << " ORDER BY "
545       expression_list_append(sql, order)
546     end
547   end
548   sql << ')'
549 
550   if group = opts[:within_group]
551     sql << " WITHIN GROUP (ORDER BY "
552     expression_list_append(sql, group)
553     sql << ')'
554   end
555 
556   if filter
557     sql << " FILTER (WHERE "
558     literal_append(sql, filter)
559     sql << ')'
560   end
561 
562   if window = opts[:over]
563     sql << ' OVER '
564     window_sql_append(sql, window.opts)
565   end
566 
567   if opts[:with_ordinality]
568     sql << " WITH ORDINALITY"
569   end
570 end
join_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN clause without ON or USING to SQL string.

    # File lib/sequel/dataset/sql.rb
573 def join_clause_sql_append(sql, jc)
574   table = jc.table
575   table_alias = jc.table_alias
576   table_alias = nil if table == table_alias && !jc.column_aliases
577   sql << ' ' << join_type_sql(jc.join_type) << ' '
578   identifier_append(sql, table)
579   as_sql_append(sql, table_alias, jc.column_aliases) if table_alias
580 end
join_on_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN ON clause to SQL string.

    # File lib/sequel/dataset/sql.rb
583 def join_on_clause_sql_append(sql, jc)
584   join_clause_sql_append(sql, jc)
585   sql << ' ON '
586   literal_append(sql, filter_expr(jc.on))
587 end
join_using_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN USING clause to SQL string.

    # File lib/sequel/dataset/sql.rb
590 def join_using_clause_sql_append(sql, jc)
591   join_clause_sql_append(sql, jc)
592   join_using_clause_using_sql_append(sql, jc.using) 
593 end
negative_boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of negative boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb
596 def negative_boolean_constant_sql_append(sql, constant)
597   sql << 'NOT '
598   boolean_constant_sql_append(sql, constant)
599 end
ordered_expression_sql_append(sql, oe) click to toggle source

Append literalization of ordered expression to SQL string.

    # File lib/sequel/dataset/sql.rb
602 def ordered_expression_sql_append(sql, oe)
603   if emulate = requires_emulating_nulls_first?
604     case oe.nulls
605     when :first
606       null_order = 0
607     when :last
608       null_order = 2
609     end
610 
611     if null_order
612       literal_append(sql, Sequel.case({{oe.expression=>nil}=>null_order}, 1))
613       sql << ", "
614     end
615   end
616 
617   literal_append(sql, oe.expression)
618   sql << (oe.descending ? ' DESC' : ' ASC')
619 
620   unless emulate
621     case oe.nulls
622     when :first
623       sql << " NULLS FIRST"
624     when :last
625       sql << " NULLS LAST"
626     end
627   end
628 end
placeholder_literal_string_sql_append(sql, pls) click to toggle source

Append literalization of placeholder literal string to SQL string.

    # File lib/sequel/dataset/sql.rb
631 def placeholder_literal_string_sql_append(sql, pls)
632   args = pls.args
633   str = pls.str
634   sql << '(' if pls.parens
635   if args.is_a?(Hash)
636     if args.empty?
637       sql << str
638     else
639       re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
640       while true
641         previous, q, str = str.partition(re)
642         sql << previous
643         literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
644         break if str.empty?
645       end
646     end
647   elsif str.is_a?(Array)
648     len = args.length
649     str.each_with_index do |s, i|
650       sql << s
651       literal_append(sql, args[i]) unless i == len
652     end
653     unless str.length == args.length || str.length == args.length + 1
654       raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
655     end
656   else
657     i = -1
658     match_len = args.length - 1
659     while true
660       previous, q, str = str.partition('?')
661       sql << previous
662       literal_append(sql, args.at(i+=1)) unless q.empty?
663       if str.empty?
664         unless i == match_len
665           raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder string"
666         end
667         break
668       end
669     end
670   end
671   sql << ')' if pls.parens
672 end
qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) click to toggle source

Append literalization of qualified identifier to SQL string. If 3 arguments are given, the 2nd should be the table/qualifier and the third should be column/qualified. If 2 arguments are given, the 2nd should be an SQL::QualifiedIdentifier.

    # File lib/sequel/dataset/sql.rb
677 def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
678   identifier_append(sql, table)
679   sql << '.'
680   identifier_append(sql, column)
681 end
quote_identifier_append(sql, name) click to toggle source

Append literalization of unqualified identifier to SQL string. Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.

    # File lib/sequel/dataset/sql.rb
687 def quote_identifier_append(sql, name)
688   if name.is_a?(LiteralString)
689     sql << name
690   else
691     name = name.value if name.is_a?(SQL::Identifier)
692     name = input_identifier(name)
693     if quote_identifiers?
694       quoted_identifier_append(sql, name)
695     else
696       sql << name
697     end
698   end
699 end
quote_schema_table_append(sql, table) click to toggle source

Append literalization of identifier or unqualified identifier to SQL string.

    # File lib/sequel/dataset/sql.rb
702 def quote_schema_table_append(sql, table)
703   schema, table = schema_and_table(table)
704   if schema
705     quote_identifier_append(sql, schema)
706     sql << '.'
707   end
708   quote_identifier_append(sql, table)
709 end
quoted_identifier_append(sql, name) click to toggle source

Append literalization of quoted identifier to SQL string. This method quotes the given name with the SQL standard double quote. should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite).

    # File lib/sequel/dataset/sql.rb
715 def quoted_identifier_append(sql, name)
716   sql << '"' << name.to_s.gsub('"', '""') << '"'
717 end
schema_and_table(table_name, sch=nil) click to toggle source

Split the schema information from the table, returning two strings, one for the schema and one for the table. The returned schema may be nil, but the table will always have a string value.

Note that this function does not handle tables with more than one level of qualification (e.g. database.schema.table on Microsoft SQL Server).

    # File lib/sequel/dataset/sql.rb
726 def schema_and_table(table_name, sch=nil)
727   sch = sch.to_s if sch
728   case table_name
729   when Symbol
730     s, t, _ = split_symbol(table_name)
731     [s||sch, t]
732   when SQL::QualifiedIdentifier
733     [table_name.table.to_s, table_name.column.to_s]
734   when SQL::Identifier
735     [sch, table_name.value.to_s]
736   when String
737     [sch, table_name]
738   else
739     raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
740   end
741 end
split_qualifiers(table_name, *args) click to toggle source

Splits table_name into an array of strings.

ds.split_qualifiers(:s) # ['s']
ds.split_qualifiers(Sequel[:t][:s]) # ['t', 's']
ds.split_qualifiers(Sequel[:d][:t][:s]) # ['d', 't', 's']
ds.split_qualifiers(Sequel.qualify(Sequel[:h][:d], Sequel[:t][:s])) # ['h', 'd', 't', 's']
    # File lib/sequel/dataset/sql.rb
749 def split_qualifiers(table_name, *args)
750   case table_name
751   when SQL::QualifiedIdentifier
752     split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
753   else
754     sch, table = schema_and_table(table_name, *args)
755     sch ? [sch, table] : [table]
756   end
757 end
subscript_sql_append(sql, s) click to toggle source

Append literalization of subscripts (SQL array accesses) to SQL string.

    # File lib/sequel/dataset/sql.rb
760 def subscript_sql_append(sql, s)
761   case s.expression
762   when Symbol, SQL::Subscript, SQL::Identifier, SQL::QualifiedIdentifier
763     # nothing
764   else
765     wrap_expression = true
766     sql << '('
767   end
768   literal_append(sql, s.expression)
769   if wrap_expression
770     sql << ')['
771   else
772     sql << '['
773   end
774   sub = s.sub
775   if sub.length == 1 && (range = sub.first).is_a?(Range)
776     literal_append(sql, range.begin)
777     sql << ':'
778     e = range.end
779     e -= 1 if range.exclude_end? && e.is_a?(Integer)
780     literal_append(sql, e)
781   else
782     expression_list_append(sql, s.sub)
783   end
784   sql << ']'
785 end
window_sql_append(sql, opts) click to toggle source

Append literalization of windows (for window functions) to SQL string.

    # File lib/sequel/dataset/sql.rb
788 def window_sql_append(sql, opts)
789   raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
790   space = false
791   space_s = ' '
792 
793   sql << '('
794 
795   if window = opts[:window]
796     literal_append(sql, window)
797     space = true
798   end
799 
800   if part = opts[:partition]
801     sql << space_s if space
802     sql << "PARTITION BY "
803     expression_list_append(sql, Array(part))
804     space = true
805   end
806 
807   if order = opts[:order]
808     sql << space_s if space
809     sql << "ORDER BY "
810     expression_list_append(sql, Array(order))
811     space = true
812   end
813 
814   if frame = opts[:frame]
815     sql << space_s if space
816 
817     if frame.is_a?(String)
818       sql << frame
819     else
820       case frame
821       when :all
822         frame_type = :rows
823         frame_start = :preceding
824         frame_end = :following
825       when :rows, :range, :groups
826         frame_type = frame
827         frame_start = :preceding
828         frame_end = :current
829       when Hash
830         frame_type = frame[:type]
831         unless frame_type == :rows || frame_type == :range || frame_type == :groups
832           raise Error, "invalid window :frame :type option: #{frame_type.inspect}"
833         end
834         unless frame_start = frame[:start]
835           raise Error, "invalid window :frame :start option: #{frame_start.inspect}"
836         end
837         frame_end = frame[:end]
838         frame_exclude = frame[:exclude]
839       else
840         raise Error, "invalid window :frame option: #{frame.inspect}"
841       end
842 
843       sql << frame_type.to_s.upcase << " "
844       sql << 'BETWEEN ' if frame_end
845       window_frame_boundary_sql_append(sql, frame_start, :preceding)
846       if frame_end
847         sql << " AND "
848         window_frame_boundary_sql_append(sql, frame_end, :following)
849       end
850 
851       if frame_exclude
852         sql << " EXCLUDE "
853 
854         case frame_exclude
855         when :current
856           sql << "CURRENT ROW"
857         when :group
858           sql << "GROUP"
859         when :ties
860           sql << "TIES"
861         when :no_others
862           sql << "NO OTHERS"
863         else
864           raise Error, "invalid window :frame :exclude option: #{frame_exclude.inspect}"
865         end
866       end
867     end
868   end
869 
870   sql << ')'
871 end

Protected Instance Methods

compound_from_self() click to toggle source

Return a from_self dataset if an order or limit is specified, so it works as expected with UNION, EXCEPT, and INTERSECT clauses.

    # File lib/sequel/dataset/sql.rb
877 def compound_from_self
878   (@opts[:sql] || @opts[:limit] || @opts[:order] || @opts[:offset]) ? from_self : self
879 end

Private Instance Methods

_check_modification_allowed!(modifying_joins_supported) click to toggle source

Internals of the check_*_allowed! methods

     # File lib/sequel/dataset/sql.rb
1071 def _check_modification_allowed!(modifying_joins_supported)
1072   raise(InvalidOperation, "Grouped datasets cannot be modified") if opts[:group]
1073   raise(InvalidOperation, "Joined datasets cannot be modified") if !modifying_joins_supported && joined_dataset?
1074 end
_insert_columns_sql(sql, columns) click to toggle source
     # File lib/sequel/dataset/sql.rb
1281 def _insert_columns_sql(sql, columns)
1282   if columns && !columns.empty?
1283     sql << ' ('
1284     identifier_list_append(sql, columns)
1285     sql << ')'
1286   end 
1287 end
_insert_values_sql(sql, values) click to toggle source
     # File lib/sequel/dataset/sql.rb
1303 def _insert_values_sql(sql, values)
1304   case values
1305   when Array
1306     if values.empty?
1307       sql << " DEFAULT VALUES"
1308     else
1309       sql << " VALUES "
1310       literal_append(sql, values)
1311     end
1312   when Dataset
1313     sql << ' '
1314     subselect_sql_append(sql, values)
1315   when LiteralString
1316     sql << ' ' << values
1317   else
1318     raise Error, "Unsupported INSERT values type, should be an Array or Dataset: #{values.inspect}"
1319   end
1320 end
_merge_delete_sql(sql, data) click to toggle source
    # File lib/sequel/dataset/sql.rb
896 def _merge_delete_sql(sql, data)
897   sql << " THEN DELETE"
898 end
_merge_insert_sql(sql, data) click to toggle source

Append the INSERT sql used in a MERGE

    # File lib/sequel/dataset/sql.rb
884 def _merge_insert_sql(sql, data)
885   sql << " THEN INSERT"
886   columns, values = _parse_insert_sql_args(data[:values])
887   _insert_columns_sql(sql, columns)
888   _insert_values_sql(sql, values)
889 end
_merge_update_sql(sql, data) click to toggle source
    # File lib/sequel/dataset/sql.rb
891 def _merge_update_sql(sql, data)
892   sql << " THEN UPDATE SET "
893   update_sql_values_hash(sql, data[:values])
894 end
_merge_when_conditions_sql(sql, data) click to toggle source

Append MERGE WHEN conditions, if there are conditions provided.

    # File lib/sequel/dataset/sql.rb
935 def _merge_when_conditions_sql(sql, data)
936   if data.has_key?(:conditions)
937     sql << " AND "
938     literal_append(sql, data[:conditions])
939   end
940 end
_merge_when_sql(sql) click to toggle source

Add the WHEN clauses to the MERGE SQL

    # File lib/sequel/dataset/sql.rb
923 def _merge_when_sql(sql)
924   raise Error, "no WHEN [NOT] MATCHED clauses provided for MERGE" unless merge_when = @opts[:merge_when]
925   merge_when.each do |data|
926     type = data[:type]
927     sql << MERGE_TYPE_SQL[type]
928     type = MERGE_NORMALIZE_TYPE_MAP[type] || type
929     _merge_when_conditions_sql(sql, data)
930     send(:"_merge_#{type}_sql", sql, data)
931   end
932 end
_parse_insert_sql_args(values) click to toggle source

Parse the values passed to insert_sql, returning columns and values to use for the INSERT. Returned columns is always an array, but can be empty for an INSERT without explicit column references. Returned values can be an array, dataset, or literal string.

    # File lib/sequel/dataset/sql.rb
946 def _parse_insert_sql_args(values)
947   columns = []
948 
949   case values.size
950   when 0
951     values = []
952   when 1
953     case vals = values[0]
954     when Hash
955       values = []
956       vals.each do |k,v| 
957         columns << k
958         values << v
959       end
960     when Dataset, Array, LiteralString
961       values = vals
962     end
963   when 2
964     if (v0 = values[0]).is_a?(Array) && ((v1 = values[1]).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
965       columns, values = v0, v1
966       raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
967     end
968   end
969 
970   [columns, values]
971 end
_truncate_sql(table) click to toggle source

Formats the truncate statement. Assumes the table given has already been literalized.

    # File lib/sequel/dataset/sql.rb
975 def _truncate_sql(table)
976   "TRUNCATE TABLE #{table}"
977 end
aggreate_dataset_use_from_self?() click to toggle source

Whether to use from_self for an aggregate dataset.

     # File lib/sequel/dataset/sql.rb
1024 def aggreate_dataset_use_from_self?
1025   options_overlap(COUNT_FROM_SELF_OPTS)
1026 end
aggregate_dataset() click to toggle source

Clone of this dataset usable in aggregate operations. Does a from_self if dataset contains any parameters that would affect normal aggregation, or just removes an existing order if not. Also removes the row_proc, which isn’t needed for aggregate calculations.

     # File lib/sequel/dataset/sql.rb
1019 def aggregate_dataset
1020   (aggreate_dataset_use_from_self? ? from_self : unordered).naked
1021 end
alias_alias_symbol(s) click to toggle source

Returns an appropriate symbol for the alias represented by s.

    # File lib/sequel/dataset/sql.rb
980 def alias_alias_symbol(s)
981   case s
982   when Symbol
983     s
984   when String
985     s.to_sym
986   when SQL::Identifier
987     s.value.to_s.to_sym
988   else
989     raise Error, "Invalid alias for alias_alias_symbol: #{s.inspect}"
990   end
991 end
alias_symbol(sym) click to toggle source

Returns an appropriate alias symbol for the given object, which can be a Symbol, String, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.

     # File lib/sequel/dataset/sql.rb
 996 def alias_symbol(sym)
 997   case sym
 998   when Symbol
 999     s, t, a = split_symbol(sym)
1000     a || s ? (a || t).to_sym : sym
1001   when String
1002     sym.to_sym
1003   when SQL::Identifier
1004     sym.value.to_s.to_sym
1005   when SQL::QualifiedIdentifier
1006     alias_symbol(sym.column)
1007   when SQL::AliasedExpression
1008     alias_alias_symbol(sym.alias)
1009   else
1010     raise Error, "Invalid alias for alias_symbol: #{sym.inspect}"
1011   end
1012 end
as_sql_append(sql, aliaz, column_aliases=nil) click to toggle source

Append aliasing expression to SQL string.

     # File lib/sequel/dataset/sql.rb
1029 def as_sql_append(sql, aliaz, column_aliases=nil)
1030   sql << ' AS '
1031   quote_identifier_append(sql, aliaz)
1032   if column_aliases
1033     raise Error, "#{db.database_type} does not support derived column lists" unless supports_derived_column_lists?
1034     sql << '('
1035     identifier_list_append(sql, column_aliases)
1036     sql << ')'
1037   end
1038 end
cache_sql?() click to toggle source

Don’t allow caching SQL if specifically marked not to.

     # File lib/sequel/dataset/sql.rb
1041 def cache_sql?
1042   !@opts[:no_cache_sql] && !cache_get(:_no_cache_sql)
1043 end
check_delete_allowed!() click to toggle source

Check whether it is allowed to delete from this dataset.

     # File lib/sequel/dataset/sql.rb
1061 def check_delete_allowed!
1062   _check_modification_allowed!(supports_deleting_joins?)
1063 end
check_insert_allowed!() click to toggle source

Check whether it is allowed to insert into this dataset.

     # File lib/sequel/dataset/sql.rb
1055 def check_insert_allowed!
1056   _check_modification_allowed!(false)
1057 end
Also aliased as: check_truncation_allowed!
check_modification_allowed!() click to toggle source

Raise an InvalidOperation exception if modification is not allowed for this dataset. Check whether it is allowed to insert into this dataset. Only for backwards compatibility with older external adapters.

     # File lib/sequel/dataset/sql.rb
1048 def check_modification_allowed!
1049   # SEQUEL6: Remove
1050   Sequel::Deprecation.deprecate("Dataset#check_modification_allowed!", "Use check_{insert,delete,update,truncation}_allowed! instead")
1051   _check_modification_allowed!(supports_modifying_joins?)
1052 end
check_not_limited!(type) click to toggle source

Raise error if the dataset uses limits or offsets.

     # File lib/sequel/dataset/sql.rb
1077 def check_not_limited!(type)
1078   return if @opts[:skip_limit_check] && type != :truncate
1079   raise InvalidOperation, "Dataset##{type} not supported on datasets with limits or offsets" if opts[:limit] || opts[:offset]
1080 end
check_truncation_allowed!()
check_update_allowed!() click to toggle source

Check whether it is allowed to update this dataset.

     # File lib/sequel/dataset/sql.rb
1066 def check_update_allowed!
1067   _check_modification_allowed!(supports_updating_joins?)
1068 end
column_list_append(sql, columns) click to toggle source

Append column list to SQL string. If the column list is empty, a wildcard (*) is appended.

     # File lib/sequel/dataset/sql.rb
1084 def column_list_append(sql, columns)
1085   if (columns.nil? || columns.empty?)
1086     sql << '*'
1087   else
1088     expression_list_append(sql, columns)
1089   end
1090 end
complex_expression_arg_pairs(args) { |args, args| ... } click to toggle source

Yield each pair of arguments to the block, which should return an object representing the SQL expression for those two arguments. For more than two arguments, the first argument to the block will be result of the previous block call.

     # File lib/sequel/dataset/sql.rb
1096 def complex_expression_arg_pairs(args)
1097   case args.length
1098   when 1
1099     args[0]
1100   when 2
1101     yield args[0], args[1]
1102   else
1103     args.inject{|m, a| yield(m, a)}
1104   end
1105 end
complex_expression_arg_pairs_append(sql, args, &block) click to toggle source

Append the literalization of the args using complex_expression_arg_pairs to the given SQL string, used when database operator/function is 2-ary where Sequel expression is N-ary.

     # File lib/sequel/dataset/sql.rb
1110 def complex_expression_arg_pairs_append(sql, args, &block)
1111   literal_append(sql, complex_expression_arg_pairs(args, &block))
1112 end
complex_expression_emulate_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string, for operators unsupported by some databases. Used by adapters for databases that don’t support the operators natively.

     # File lib/sequel/dataset/sql.rb
1117 def complex_expression_emulate_append(sql, op, args)
1118   # :nocov:
1119   case op
1120   # :nocov:
1121   when :%
1122     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.function(:MOD, a, b)}
1123   when :>>
1124     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel./(a, Sequel.function(:power, 2, b))}
1125   when :<<
1126     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.*(a, Sequel.function(:power, 2, b))}
1127   when :&, :|, :^
1128     f = BITWISE_METHOD_MAP[op]
1129     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.function(f, a, b)}
1130   when :'B~'
1131     sql << "((0 - "
1132     literal_append(sql, args[0])
1133     sql << ") - 1)"
1134   end
1135 end
compound_dataset_sql_append(sql, ds) click to toggle source

Append literalization of dataset used in UNION/INTERSECT/EXCEPT clause to SQL string.

     # File lib/sequel/dataset/sql.rb
1138 def compound_dataset_sql_append(sql, ds)
1139   subselect_sql_append(sql, ds)
1140 end
dataset_alias(number) click to toggle source

The alias to use for datasets, takes a number to make sure the name is unique.

     # File lib/sequel/dataset/sql.rb
1143 def dataset_alias(number)
1144   :"t#{number}"
1145 end
default_time_format() click to toggle source

The strftime format to use when literalizing time (Sequel::SQLTime) values.

     # File lib/sequel/dataset/sql.rb
1148 def default_time_format
1149   "'%H:%M:%S.%6N'"
1150 end
default_timestamp_format() click to toggle source

The strftime format to use when literalizing timestamp (Time/DateTime) values.

     # File lib/sequel/dataset/sql.rb
1153 def default_timestamp_format
1154   "'%Y-%m-%d %H:%M:%S.%6N'"
1155 end
delete_delete_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1157 def delete_delete_sql(sql)
1158   sql << 'DELETE'
1159 end
delete_from_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1161 def delete_from_sql(sql)
1162   if f = @opts[:from]
1163     sql << ' FROM '
1164     source_list_append(sql, f)
1165   end
1166 end
delete_order_sql(sql)
Alias for: select_order_sql
delete_returning_sql(sql)
delete_where_sql(sql)
Alias for: select_where_sql
delete_with_sql(sql)
Alias for: select_with_sql
disable_sql_caching!() click to toggle source

Disable caching of SQL for the current dataset

     # File lib/sequel/dataset/sql.rb
1169 def disable_sql_caching!
1170   cache_set(:_no_cache_sql, true)
1171 end
empty_array_value(op, cols) click to toggle source

An expression for how to handle an empty array lookup.

     # File lib/sequel/dataset/sql.rb
1213 def empty_array_value(op, cols)
1214   {1 => ((op == :IN) ? 0 : 1)}
1215 end
empty_from_sql() click to toggle source

An SQL FROM clause to use in SELECT statements where the dataset has no from tables.

     # File lib/sequel/dataset/sql.rb
1175 def empty_from_sql
1176   nil
1177 end
emulate_function?(name) click to toggle source

Whether to emulate the function with the given name. This should only be true if the emulation goes beyond choosing a function with a different name.

     # File lib/sequel/dataset/sql.rb
1181 def emulate_function?(name)
1182   false
1183 end
expression_list_append(sql, columns) click to toggle source

Append literalization of array of expressions to SQL string, separating them with commas.

     # File lib/sequel/dataset/sql.rb
1187 def expression_list_append(sql, columns)
1188   c = false
1189   co = ', '
1190   columns.each do |col|
1191     sql << co if c
1192     literal_append(sql, col)
1193     c ||= true
1194   end
1195 end
format_timestamp(v) click to toggle source

Format the timestamp based on the default_timestamp_format.

     # File lib/sequel/dataset/sql.rb
1218 def format_timestamp(v)
1219   db.from_application_timestamp(v).strftime(default_timestamp_format)
1220 end
format_timestamp_usec(usec, ts=timestamp_precision) click to toggle source

Return the SQL timestamp fragment to use for the fractional time part. Should start with the decimal point. Uses 6 decimal places by default.

     # File lib/sequel/dataset/sql.rb
1226 def format_timestamp_usec(usec, ts=timestamp_precision)
1227   # SEQUEL6: Remove
1228   unless ts == 6
1229     usec = usec/(10 ** (6 - ts))
1230   end
1231   sprintf(".%0#{ts}d", usec)
1232 end
grouping_element_list_append(sql, columns) click to toggle source

Append literalization of array of grouping elements to SQL string, seperating them with commas.

     # File lib/sequel/dataset/sql.rb
1198 def grouping_element_list_append(sql, columns)
1199   c = false
1200   co = ', '
1201   columns.each do |col|
1202     sql << co if c
1203     if col.is_a?(Array) && col.empty?
1204       sql << '()'
1205     else
1206       literal_append(sql, Array(col))
1207     end
1208     c ||= true
1209   end
1210 end
identifier_append(sql, v) click to toggle source

Append literalization of identifier to SQL string, considering regular strings as SQL identifiers instead of SQL strings.

     # File lib/sequel/dataset/sql.rb
1237 def identifier_append(sql, v)
1238   if v.is_a?(String)
1239     case v
1240     when LiteralString
1241       sql << v
1242     when SQL::Blob
1243       literal_append(sql, v)
1244     else
1245       quote_identifier_append(sql, v)
1246     end
1247   else
1248     literal_append(sql, v)
1249   end
1250 end
identifier_list_append(sql, args) click to toggle source

Append literalization of array of identifiers to SQL string.

     # File lib/sequel/dataset/sql.rb
1253 def identifier_list_append(sql, args)
1254   c = false
1255   comma = ', '
1256   args.each do |a|
1257     sql << comma if c
1258     identifier_append(sql, a)
1259     c ||= true
1260   end
1261 end
input_identifier(v) click to toggle source

Upcase identifiers by default when inputting them into the database.

     # File lib/sequel/dataset/sql.rb
1264 def input_identifier(v)
1265   v.to_s.upcase
1266 end
insert_columns_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1277 def insert_columns_sql(sql)
1278   _insert_columns_sql(sql, opts[:columns])
1279 end
insert_empty_columns_values() click to toggle source

The columns and values to use for an empty insert if the database doesn’t support INSERT with DEFAULT VALUES.

     # File lib/sequel/dataset/sql.rb
1291 def insert_empty_columns_values
1292   [[columns.last], [DEFAULT]]
1293 end
insert_insert_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1295 def insert_insert_sql(sql)
1296   sql << "INSERT"
1297 end
insert_into_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1268 def insert_into_sql(sql)
1269   sql << " INTO "
1270   if (f = @opts[:from]) && f.length == 1
1271     identifier_append(sql, unaliased_identifier(f.first))
1272   else
1273     source_list_append(sql, f)
1274   end
1275 end
insert_returning_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1322 def insert_returning_sql(sql)
1323   if opts.has_key?(:returning)
1324     sql << " RETURNING "
1325     column_list_append(sql, Array(opts[:returning]))
1326   end
1327 end
insert_values_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1299 def insert_values_sql(sql)
1300   _insert_values_sql(sql, opts[:values])
1301 end
insert_with_sql(sql)
Alias for: select_with_sql
join_type_sql(join_type) click to toggle source

SQL fragment specifying a JOIN type, converts underscores to spaces and upcases.

     # File lib/sequel/dataset/sql.rb
1333 def join_type_sql(join_type)
1334   "#{join_type.to_s.gsub('_', ' ').upcase} JOIN"
1335 end
join_using_clause_using_sql_append(sql, using_columns) click to toggle source

Append USING clause for JOIN USING

     # File lib/sequel/dataset/sql.rb
1338 def join_using_clause_using_sql_append(sql, using_columns)
1339   sql << ' USING ('
1340   column_list_append(sql, using_columns)
1341   sql << ')'
1342 end
literal_array_append(sql, v) click to toggle source

Append a literalization of the array to SQL string. Treats as an expression if an array of all two pairs, or as a SQL array otherwise.

     # File lib/sequel/dataset/sql.rb
1346 def literal_array_append(sql, v)
1347   if Sequel.condition_specifier?(v)
1348     literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
1349   else
1350     array_sql_append(sql, v)
1351   end
1352 end
literal_big_decimal(v) click to toggle source

SQL fragment for BigDecimal

     # File lib/sequel/dataset/sql.rb
1355 def literal_big_decimal(v)
1356   d = v.to_s("F")
1357   v.nan? || v.infinite? ?  "'#{d}'" : d
1358 end
literal_blob_append(sql, v) click to toggle source

Append literalization of SQL::Blob to SQL string.

     # File lib/sequel/dataset/sql.rb
1361 def literal_blob_append(sql, v)
1362   literal_string_append(sql, v)
1363 end
literal_dataset_append(sql, v) click to toggle source

Append literalization of dataset to SQL string. Does a subselect inside parantheses.

     # File lib/sequel/dataset/sql.rb
1366 def literal_dataset_append(sql, v)
1367   sql << 'LATERAL ' if v.opts[:lateral]
1368   sql << '('
1369   subselect_sql_append(sql, v)
1370   sql << ')'
1371 end
literal_date(v) click to toggle source

SQL fragment for Date, using the ISO8601 format.

     # File lib/sequel/dataset/sql.rb
1374 def literal_date(v)
1375   v.strftime("'%Y-%m-%d'")
1376 end
literal_date_append(sql, v) click to toggle source

Append literalization of date to SQL string.

     # File lib/sequel/dataset/sql.rb
1379 def literal_date_append(sql, v)
1380   sql << literal_date(v)
1381 end
literal_datetime(v) click to toggle source

SQL fragment for DateTime

     # File lib/sequel/dataset/sql.rb
1384 def literal_datetime(v)
1385   format_timestamp(v)
1386 end
literal_datetime_append(sql, v) click to toggle source

Append literalization of DateTime to SQL string.

     # File lib/sequel/dataset/sql.rb
1389 def literal_datetime_append(sql, v)
1390   sql << literal_datetime(v)
1391 end
literal_expression_append(sql, v) click to toggle source

Append literalization of SQL::Expression to SQL string.

     # File lib/sequel/dataset/sql.rb
1394 def literal_expression_append(sql, v)
1395   v.to_s_append(self, sql)
1396 end
literal_false() click to toggle source

SQL fragment for false

     # File lib/sequel/dataset/sql.rb
1399 def literal_false
1400   "'f'"
1401 end
literal_float(v) click to toggle source

SQL fragment for Float

     # File lib/sequel/dataset/sql.rb
1404 def literal_float(v)
1405   v.to_s
1406 end
literal_hash_append(sql, v) click to toggle source

Append literalization of Hash to SQL string, treating hash as a boolean expression.

     # File lib/sequel/dataset/sql.rb
1409 def literal_hash_append(sql, v)
1410   literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
1411 end
literal_integer(v) click to toggle source

SQL fragment for Integer

     # File lib/sequel/dataset/sql.rb
1414 def literal_integer(v)
1415   v.to_s
1416 end
literal_nil() click to toggle source

SQL fragment for nil

     # File lib/sequel/dataset/sql.rb
1419 def literal_nil
1420   "NULL"
1421 end
literal_other_append(sql, v) click to toggle source

Append a literalization of the object to the given SQL string. Calls sql_literal_append if object responds to it, otherwise calls sql_literal if object responds to it, otherwise raises an error. If a database specific type is allowed, this should be overriden in a subclass.

     # File lib/sequel/dataset/sql.rb
1427 def literal_other_append(sql, v)
1428   # We can't be sure if v will always literalize to the same SQL, so
1429   # don't cache SQL for a dataset that uses this.
1430   disable_sql_caching!
1431 
1432   if v.respond_to?(:sql_literal_append)
1433     v.sql_literal_append(self, sql)
1434   elsif v.respond_to?(:sql_literal)
1435     sql << v.sql_literal(self)
1436   else
1437     raise Error, "can't express #{v.inspect} as a SQL literal"
1438   end
1439 end
literal_sqltime(v) click to toggle source

SQL fragment for Sequel::SQLTime, containing just the time part

     # File lib/sequel/dataset/sql.rb
1442 def literal_sqltime(v)
1443   v.strftime(default_time_format)
1444 end
literal_sqltime_append(sql, v) click to toggle source

Append literalization of Sequel::SQLTime to SQL string.

     # File lib/sequel/dataset/sql.rb
1447 def literal_sqltime_append(sql, v)
1448   sql << literal_sqltime(v)
1449 end
literal_string_append(sql, v) click to toggle source

Append literalization of string to SQL string.

     # File lib/sequel/dataset/sql.rb
1452 def literal_string_append(sql, v)
1453   sql << "'" << v.gsub("'", "''") << "'"
1454 end
literal_symbol_append(sql, v) click to toggle source

Append literalization of symbol to SQL string.

     # File lib/sequel/dataset/sql.rb
1457 def literal_symbol_append(sql, v)
1458   c_table, column, c_alias = split_symbol(v)
1459   if c_table
1460     quote_identifier_append(sql, c_table)
1461     sql << '.'
1462   end
1463   quote_identifier_append(sql, column)
1464   as_sql_append(sql, c_alias) if c_alias
1465 end
literal_time(v) click to toggle source

SQL fragment for Time

     # File lib/sequel/dataset/sql.rb
1468 def literal_time(v)
1469   format_timestamp(v)
1470 end
literal_time_append(sql, v) click to toggle source

Append literalization of Time to SQL string.

     # File lib/sequel/dataset/sql.rb
1473 def literal_time_append(sql, v)
1474   sql << literal_time(v)
1475 end
literal_true() click to toggle source

SQL fragment for true

     # File lib/sequel/dataset/sql.rb
1478 def literal_true
1479   "'t'"
1480 end
multi_insert_sql_strategy() click to toggle source

What strategy to use for import/multi_insert. While SQL-92 defaults to allowing multiple rows in a VALUES clause, there are enough databases that don’t allow that that it can’t be the default. Use separate queries by default, which works everywhere.

     # File lib/sequel/dataset/sql.rb
1486 def multi_insert_sql_strategy
1487   :separate
1488 end
native_function_name(emulated_function) click to toggle source

Get the native function name given the emulated function name.

     # File lib/sequel/dataset/sql.rb
1492 def native_function_name(emulated_function)
1493   emulated_function
1494 end
qualified_column_name(column, table) click to toggle source

Returns a qualified column name (including a table name) if the column name isn’t already qualified.

     # File lib/sequel/dataset/sql.rb
1498 def qualified_column_name(column, table)
1499   if column.is_a?(Symbol)
1500     c_table, column, _ = split_symbol(column)
1501     unless c_table
1502       case table
1503       when Symbol
1504         schema, table, t_alias = split_symbol(table)
1505         t_alias ||= Sequel::SQL::QualifiedIdentifier.new(schema, table) if schema
1506       when Sequel::SQL::AliasedExpression
1507         t_alias = table.alias
1508       end
1509       c_table = t_alias || table
1510     end
1511     ::Sequel::SQL::QualifiedIdentifier.new(c_table, column)
1512   else
1513     column
1514   end
1515 end
qualified_expression(e, table) click to toggle source

Qualify the given expression to the given table.

     # File lib/sequel/dataset/sql.rb
1518 def qualified_expression(e, table)
1519   Qualifier.new(table).transform(e)
1520 end
select_columns_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1522 def select_columns_sql(sql)
1523   sql << ' '
1524   column_list_append(sql, @opts[:select])
1525 end
select_compounds_sql(sql) click to toggle source

Modify the sql to add a dataset to the via an EXCEPT, INTERSECT, or UNION clause. This uses a subselect for the compound datasets used, because using parantheses doesn’t work on all databases.

     # File lib/sequel/dataset/sql.rb
1541 def select_compounds_sql(sql)
1542   return unless c = @opts[:compounds]
1543   c.each do |type, dataset, all|
1544     sql << ' ' << type.to_s.upcase
1545     sql << ' ALL' if all
1546     sql << ' '
1547     compound_dataset_sql_append(sql, dataset)
1548   end
1549 end
select_distinct_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1527 def select_distinct_sql(sql)
1528   if distinct = @opts[:distinct]
1529     sql << " DISTINCT"
1530     unless distinct.empty?
1531       sql << " ON ("
1532       expression_list_append(sql, distinct)
1533       sql << ')'
1534     end
1535   end
1536 end
select_from_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1551 def select_from_sql(sql)
1552   if f = @opts[:from]
1553     sql << ' FROM '
1554     source_list_append(sql, f)
1555   elsif f = empty_from_sql
1556     sql << f
1557   end
1558 end
select_group_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1560 def select_group_sql(sql)
1561   if group = @opts[:group]
1562     sql << " GROUP BY "
1563     if go = @opts[:group_options]
1564       if go == :"grouping sets"
1565         sql << go.to_s.upcase << '('
1566         grouping_element_list_append(sql, group)
1567         sql << ')'
1568       elsif uses_with_rollup?
1569         expression_list_append(sql, group)
1570         sql << " WITH " << go.to_s.upcase
1571       else
1572         sql << go.to_s.upcase << '('
1573         expression_list_append(sql, group)
1574         sql << ')'
1575       end
1576     else
1577       expression_list_append(sql, group)
1578     end
1579   end
1580 end
select_having_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1582 def select_having_sql(sql)
1583   if having = @opts[:having]
1584     sql << " HAVING "
1585     literal_append(sql, having)
1586   end
1587 end
select_join_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1589 def select_join_sql(sql)
1590   if js = @opts[:join]
1591     js.each{|j| literal_append(sql, j)}
1592   end
1593 end
select_limit_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1595 def select_limit_sql(sql)
1596   if l = @opts[:limit]
1597     sql << " LIMIT "
1598     literal_append(sql, l)
1599     if o = @opts[:offset]
1600       sql << " OFFSET "
1601       literal_append(sql, o)
1602     end
1603   elsif @opts[:offset]
1604     select_only_offset_sql(sql)
1605   end
1606 end
select_lock_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1608 def select_lock_sql(sql)
1609   case l = @opts[:lock]
1610   when :update
1611     sql << ' FOR UPDATE'
1612   when String
1613     sql << ' ' << l
1614   end
1615 end
select_only_offset_sql(sql) click to toggle source

Used only if there is an offset and no limit, making it easier to override in the adapter, as many databases do not support just a plain offset with no limit.

     # File lib/sequel/dataset/sql.rb
1620 def select_only_offset_sql(sql)
1621   sql << " OFFSET "
1622   literal_append(sql, @opts[:offset])
1623 end
select_order_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1625 def select_order_sql(sql)
1626   if o = @opts[:order]
1627     sql << " ORDER BY "
1628     expression_list_append(sql, o)
1629   end
1630 end
select_select_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1634 def select_select_sql(sql)
1635   sql << 'SELECT'
1636 end
select_where_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1638 def select_where_sql(sql)
1639   if w = @opts[:where]
1640     sql << " WHERE "
1641     literal_append(sql, w)
1642   end
1643 end
select_window_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1647 def select_window_sql(sql)
1648   if ws = @opts[:window]
1649     sql << " WINDOW "
1650     c = false
1651     co = ', '
1652     as = ' AS '
1653     ws.map do |name, window|
1654       sql << co if c
1655       literal_append(sql, name)
1656       sql << as
1657       literal_append(sql, window)
1658       c ||= true
1659     end
1660   end
1661 end
select_with_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1663 def select_with_sql(sql)
1664   return unless supports_cte?
1665   ctes = opts[:with]
1666   return if !ctes || ctes.empty?
1667   sql << select_with_sql_base
1668   c = false
1669   comma = ', '
1670   ctes.each do |cte|
1671     sql << comma if c
1672     select_with_sql_cte(sql, cte)
1673     c ||= true
1674   end
1675   sql << ' '
1676 end
select_with_sql_base() click to toggle source
     # File lib/sequel/dataset/sql.rb
1681 def select_with_sql_base
1682   "WITH "
1683 end
select_with_sql_cte(sql, cte) click to toggle source
     # File lib/sequel/dataset/sql.rb
1685 def select_with_sql_cte(sql, cte)
1686   select_with_sql_prefix(sql, cte)
1687   literal_dataset_append(sql, cte[:dataset])
1688 end
select_with_sql_prefix(sql, w) click to toggle source
     # File lib/sequel/dataset/sql.rb
1690 def select_with_sql_prefix(sql, w)
1691   quote_identifier_append(sql, w[:name])
1692   if args = w[:args]
1693    sql << '('
1694    identifier_list_append(sql, args)
1695    sql << ')'
1696   end
1697   sql << ' AS '
1698 
1699   case w[:materialized]
1700   when true
1701     sql << "MATERIALIZED "
1702   when false
1703     sql << "NOT MATERIALIZED "
1704   end
1705 end
skip_symbol_cache?() click to toggle source

Whether the symbol cache should be skipped when literalizing the dataset

     # File lib/sequel/dataset/sql.rb
1708 def skip_symbol_cache?
1709   @opts[:skip_symbol_cache]
1710 end
source_list_append(sql, sources) click to toggle source

Append literalization of array of sources/tables to SQL string, raising an Error if there are no sources.

     # File lib/sequel/dataset/sql.rb
1714 def source_list_append(sql, sources)
1715   raise(Error, 'No source specified for query') if sources.nil? || sources == []
1716   identifier_list_append(sql, sources)
1717 end
split_symbol(sym) click to toggle source

Delegate to Sequel.split_symbol.

     # File lib/sequel/dataset/sql.rb
1720 def split_symbol(sym)
1721   Sequel.split_symbol(sym)
1722 end
sql_string_origin() click to toggle source

The string that is appended to to create the SQL query, the empty string by default.

     # File lib/sequel/dataset/sql.rb
1726 def sql_string_origin
1727   String.new
1728 end
sqltime_precision() click to toggle source

The precision to use for SQLTime instances (time column values without dates). Defaults to timestamp_precision.

     # File lib/sequel/dataset/sql.rb
1732 def sqltime_precision
1733   timestamp_precision
1734 end
static_sql(sql) click to toggle source

SQL to use if this dataset uses static SQL. Since static SQL can be a PlaceholderLiteralString in addition to a String, we literalize nonstrings. If there is an append_sql for this dataset, append to that SQL instead of returning the value.

     # File lib/sequel/dataset/sql.rb
1740 def static_sql(sql)
1741   if append_sql = @opts[:append_sql]
1742     if sql.is_a?(String)
1743       append_sql << sql
1744     else
1745       literal_append(append_sql, sql)
1746     end
1747   else
1748     if sql.is_a?(String)
1749       sql
1750     else
1751       literal(sql)
1752     end
1753   end
1754 end
subselect_sql_append(sql, ds) click to toggle source

Append literalization of the subselect to SQL string.

     # File lib/sequel/dataset/sql.rb
1757 def subselect_sql_append(sql, ds)
1758   sds = subselect_sql_dataset(sql, ds)
1759   subselect_sql_append_sql(sql, sds)
1760   unless sds.send(:cache_sql?)
1761     # If subquery dataset does not allow caching SQL,
1762     # then this dataset should not allow caching SQL.
1763     disable_sql_caching!
1764   end
1765 end
subselect_sql_append_sql(sql, ds) click to toggle source
     # File lib/sequel/dataset/sql.rb
1771 def subselect_sql_append_sql(sql, ds)
1772   ds.sql
1773 end
subselect_sql_dataset(sql, ds) click to toggle source
     # File lib/sequel/dataset/sql.rb
1767 def subselect_sql_dataset(sql, ds)
1768   ds.clone(:append_sql=>sql)
1769 end
timestamp_precision() click to toggle source

The number of decimal digits of precision to use in timestamps.

     # File lib/sequel/dataset/sql.rb
1776 def timestamp_precision
1777   supports_timestamp_usecs? ? 6 : 0
1778 end
update_order_sql(sql)
Alias for: select_order_sql
update_returning_sql(sql)
update_set_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1786 def update_set_sql(sql)
1787   sql << ' SET '
1788   values = @opts[:values]
1789   if values.is_a?(Hash)
1790     update_sql_values_hash(sql, values)
1791   else
1792     sql << values
1793   end
1794 end
update_sql_values_hash(sql, values) click to toggle source
     # File lib/sequel/dataset/sql.rb
1796 def update_sql_values_hash(sql, values)
1797   c = false
1798   eq = ' = '
1799   values.each do |k, v|
1800     sql << ', ' if c
1801     if k.is_a?(String) && !k.is_a?(LiteralString)
1802       quote_identifier_append(sql, k)
1803     else
1804       literal_append(sql, k)
1805     end
1806     sql << eq
1807     literal_append(sql, v)
1808     c ||= true
1809   end
1810 end
update_table_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1780 def update_table_sql(sql)
1781   sql << ' '
1782   source_list_append(sql, @opts[:from])
1783   select_join_sql(sql) if supports_modifying_joins?
1784 end
update_update_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1812 def update_update_sql(sql)
1813   sql << 'UPDATE'
1814 end
update_where_sql(sql)
Alias for: select_where_sql
update_with_sql(sql)
Alias for: select_with_sql
window_frame_boundary_sql_append(sql, boundary, direction) click to toggle source
     # File lib/sequel/dataset/sql.rb
1816 def window_frame_boundary_sql_append(sql, boundary, direction)
1817   case boundary
1818   when :current
1819    sql << "CURRENT ROW"
1820   when :preceding
1821     sql << "UNBOUNDED PRECEDING"
1822   when :following
1823     sql << "UNBOUNDED FOLLOWING"
1824   else
1825     if boundary.is_a?(Array)
1826       offset, direction = boundary
1827       unless boundary.length == 2 && (direction == :preceding || direction == :following)
1828         raise Error, "invalid window :frame boundary (:start or :end) option: #{boundary.inspect}"
1829       end
1830     else
1831       offset = boundary
1832     end
1833 
1834     case offset
1835     when Numeric, String, SQL::Cast
1836       # nothing
1837     else
1838       raise Error, "invalid window :frame boundary (:start or :end) option: #{boundary.inspect}"
1839     end
1840 
1841     literal_append(sql, offset)
1842     sql << (direction == :preceding ? " PRECEDING" : " FOLLOWING")
1843   end
1844 end