class Sequel::Dataset

  1. lib/sequel/dataset.rb
  2. lib/sequel/dataset/actions.rb
  3. lib/sequel/dataset/dataset_module.rb
  4. lib/sequel/dataset/deprecated_singleton_class_methods.rb
  5. lib/sequel/dataset/features.rb
  6. lib/sequel/dataset/graph.rb
  7. lib/sequel/dataset/misc.rb
  8. lib/sequel/dataset/placeholder_literalizer.rb
  9. lib/sequel/dataset/prepared_statements.rb
  10. lib/sequel/dataset/query.rb
  11. lib/sequel/dataset/sql.rb
  12. lib/sequel/model/base.rb
  13. lib/sequel/sql.rb
  14. show all
Superclass: Object

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.

Methods

Public Class

  1. clause_methods
  2. def_sql_method
  3. new
  4. register_extension

Public Instance

  1. <<
  2. ==
  3. []
  4. add_graph_aliases
  5. aliased_expression_sql_append
  6. all
  7. array_sql_append
  8. as_hash
  9. avg
  10. bind
  11. boolean_constant_sql_append
  12. call
  13. case_expression_sql_append
  14. cast_sql_append
  15. clone
  16. column_all_sql_append
  17. columns
  18. columns!
  19. complex_expression_sql_append
  20. constant_sql_append
  21. count
  22. current_datetime
  23. db
  24. delayed_evaluation_sql_append
  25. delete
  26. distinct
  27. dup
  28. each
  29. each_server
  30. empty?
  31. eql?
  32. escape_like
  33. except
  34. exclude
  35. exclude_having
  36. exists
  37. extension
  38. filter
  39. first
  40. first!
  41. first_source
  42. first_source_alias
  43. first_source_table
  44. for_update
  45. freeze
  46. from
  47. from_self
  48. function_sql_append
  49. get
  50. graph
  51. grep
  52. group
  53. group_and_count
  54. group_append
  55. group_by
  56. group_cube
  57. group_rollup
  58. grouping_sets
  59. hash
  60. having
  61. import
  62. insert
  63. insert_sql
  64. inspect
  65. intersect
  66. invert
  67. join
  68. join_clause_sql_append
  69. join_on_clause_sql_append
  70. join_table
  71. join_using_clause_sql_append
  72. joined_dataset?
  73. last
  74. lateral
  75. limit
  76. literal_append
  77. literal_date_or_time
  78. lock_style
  79. map
  80. max
  81. merge
  82. merge_delete
  83. merge_insert
  84. merge_sql
  85. merge_update
  86. merge_using
  87. min
  88. multi_insert
  89. multi_insert_sql
  90. naked
  91. negative_boolean_constant_sql_append
  92. nowait
  93. offset
  94. opts
  95. or
  96. order
  97. order_append
  98. order_by
  99. order_more
  100. order_prepend
  101. ordered_expression_sql_append
  102. paged_each
  103. placeholder_literal_string_sql_append
  104. placeholder_literalizer_class
  105. placeholder_literalizer_loader
  106. prepare
  107. provides_accurate_rows_matched?
  108. qualified_identifier_sql_append
  109. qualify
  110. quote_identifier_append
  111. quote_identifiers?
  112. quote_schema_table_append
  113. quoted_identifier_append
  114. recursive_cte_requires_column_aliases?
  115. requires_placeholder_type_specifiers?
  116. requires_sql_standard_datetimes?
  117. returning
  118. reverse
  119. reverse_order
  120. row_number_column
  121. row_proc
  122. schema_and_table
  123. select
  124. select_all
  125. select_append
  126. select_group
  127. select_hash
  128. select_hash_groups
  129. select_map
  130. select_more
  131. select_order_map
  132. server
  133. server?
  134. set_graph_aliases
  135. single_record
  136. single_record!
  137. single_value
  138. single_value!
  139. skip_limit_check
  140. skip_locked
  141. split_alias
  142. split_qualifiers
  143. sql
  144. subscript_sql_append
  145. sum
  146. supports_cte?
  147. supports_cte_in_subqueries?
  148. supports_deleting_joins?
  149. supports_derived_column_lists?
  150. supports_distinct_on?
  151. supports_group_cube?
  152. supports_group_rollup?
  153. supports_grouping_sets?
  154. supports_insert_select?
  155. supports_intersect_except?
  156. supports_intersect_except_all?
  157. supports_is_true?
  158. supports_join_using?
  159. supports_lateral_subqueries?
  160. supports_limits_in_correlated_subqueries?
  161. supports_merge?
  162. supports_modifying_joins?
  163. supports_multiple_column_in?
  164. supports_nowait?
  165. supports_offsets_in_correlated_subqueries?
  166. supports_ordered_distinct_on?
  167. supports_placeholder_literalizer?
  168. supports_regexp?
  169. supports_replace?
  170. supports_returning?
  171. supports_select_all_and_column?
  172. supports_skip_locked?
  173. supports_timestamp_timezones?
  174. supports_timestamp_usecs?
  175. supports_updating_joins?
  176. supports_where_true?
  177. supports_window_clause?
  178. supports_window_function_frame_option?
  179. supports_window_functions?
  180. to_hash
  181. to_hash_groups
  182. truncate
  183. truncate_sql
  184. unfiltered
  185. ungraphed
  186. ungrouped
  187. union
  188. unlimited
  189. unordered
  190. unqualified_column_for
  191. unused_table_alias
  192. update
  193. update_sql
  194. where
  195. where_all
  196. where_each
  197. where_single_value
  198. window
  199. window_sql_append
  200. with
  201. with_extend
  202. with_quote_identifiers
  203. with_recursive
  204. with_row_proc
  205. with_sql
  206. with_sql_all
  207. with_sql_delete
  208. with_sql_each
  209. with_sql_first
  210. with_sql_insert
  211. with_sql_single_value

Protected Instance

  1. _columns
  2. _import
  3. _select_map_multiple
  4. _select_map_single
  5. cache
  6. cache_get
  7. cache_set
  8. clear_columns_cache
  9. compound_clone
  10. compound_from_self
  11. options_overlap
  12. simple_select_all?
  13. single_value_ds
  14. to_prepared_statement

Constants

OPTS = Sequel::OPTS  
TRUE_FREEZE = RUBY_VERSION >= '2.4'  

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

Constants

COLUMN_CHANGE_OPTS = [:select, :sql, :from, :join].freeze  

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

CONDITIONED_JOIN_TYPES = [:inner, :full_outer, :right_outer, :left_outer, :full, :right, :left].freeze  

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 = [].freeze  
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).

JOIN_METHODS = ((CONDITIONED_JOIN_TYPES + UNCONDITIONED_JOIN_TYPES).map{|x| "#{x}_join".to_sym} + [:join, :join_table]).freeze  

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

NON_SQL_OPTIONS = [:server, :graph, :row_proc, :quote_identifiers, :skip_symbol_cache].freeze  

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 = ((<<-METHS).split.map(&:to_sym) + JOIN_METHODS).freeze  

Methods that return modified datasets

SIMPLE_SELECT_ALL_ALLOWED_FROM = [Symbol, SQL::Identifier, SQL::QualifiedIdentifier].freeze  

From types allowed to be considered a simple_select_all

UNCONDITIONED_JOIN_TYPES = [:natural, :natural_left, :natural_right, :natural_full, :cross].freeze  

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 Instance Aliases

_clone -> clone

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

Public Class methods

register_extension(ext, mod=nil, &block)

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.

[show source]
   # 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))

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.

[show source]
   # 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
distinct(*args, &block)

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+.

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

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
[show source]
    # File lib/sequel/dataset/query.rb
156 def except(dataset, opts=OPTS)
157   raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
158   raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
159   compound_clone(:except, dataset, opts)
160 end
exclude(*cond, &block)

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'))
[show source]
    # File lib/sequel/dataset/query.rb
186 def exclude(*cond, &block)
187   add_filter(:where, cond, true, &block)
188 end
exclude_having(*cond, &block)

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.

[show source]
    # File lib/sequel/dataset/query.rb
197 def exclude_having(*cond, &block)
198   add_filter(:having, cond, true, &block)
199 end
extension(*exts)

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.

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

Alias for where.

[show source]
    # File lib/sequel/dataset/query.rb
225 def filter(*cond, &block)
226   where(*cond, &block)
227 end
for_update()

Returns a cloned dataset with a :update lock style.

DB[:table].for_update # SELECT * FROM table FOR UPDATE
[show source]
    # File lib/sequel/dataset/query.rb
232 def for_update
233   cached_dataset(:_for_update_ds){lock_style(:update)}
234 end
from(*source, &block)

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

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)
[show source]
    # File lib/sequel/dataset/query.rb
293 def from_self(opts=OPTS)
294   fs = {}
295   @opts.keys.each{|k| fs[k] = nil unless non_sql_option?(k)}
296   pr = proc do
297     c = clone(fs).from(opts[:alias] ? as(opts[:alias], opts[:column_aliases]) : self)
298     if cols = _columns
299       c.send(:columns=, cols)
300     end
301     c
302   end
303 
304   opts.empty? ? cached_dataset(:_from_self_ds, &pr) : pr.call
305 end
grep(columns, patterns, opts=OPTS)

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 '\'))
[show source]
    # File lib/sequel/dataset/query.rb
342 def grep(columns, patterns, opts=OPTS)
343   column_op = opts[:all_columns] ? :AND : :OR
344   if opts[:all_patterns]
345     conds = Array(patterns).map do |pat|
346       SQL::BooleanExpression.new(column_op, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
347     end
348     where(SQL::BooleanExpression.new(:AND, *conds))
349   else
350     conds = Array(columns).map do |c|
351       SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
352     end
353     where(SQL::BooleanExpression.new(column_op, *conds))
354   end
355 end
group(*columns, &block)

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)
[show source]
    # File lib/sequel/dataset/query.rb
364 def group(*columns, &block)
365   virtual_row_columns(columns, block)
366   clone(:group => (columns.compact.empty? ? nil : columns.freeze))
367 end
group_and_count(*columns, &block)

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}, ...]
[show source]
    # File lib/sequel/dataset/query.rb
395 def group_and_count(*columns, &block)
396   select_group(*columns, &block).select_append(COUNT_OF_ALL_AS_COUNT)
397 end
group_append(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
405 def group_append(*columns, &block)
406   columns = @opts[:group] + columns if @opts[:group]
407   group(*columns, &block)
408 end
group_by(*columns, &block)

Alias of group

[show source]
    # File lib/sequel/dataset/query.rb
370 def group_by(*columns, &block)
371   group(*columns, &block)
372 end
group_cube()

Adds the appropriate CUBE syntax to GROUP BY.

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

Adds the appropriate ROLLUP syntax to GROUP BY.

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

Adds the appropriate GROUPING SETS syntax to GROUP BY.

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

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)
[show source]
    # File lib/sequel/dataset/query.rb
432 def having(*cond, &block)
433   add_filter(:having, cond, &block)
434 end
intersect(dataset, opts=OPTS)

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
[show source]
    # File lib/sequel/dataset/query.rb
453 def intersect(dataset, opts=OPTS)
454   raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
455   raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
456   compound_clone(:intersect, dataset, opts)
457 end
invert()

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.

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

Alias of inner_join

[show source]
    # File lib/sequel/dataset/query.rb
485 def join(*args, &block)
486   inner_join(*args, &block)
487 end
join_table(type, table, expr=nil, options=OPTS, &block)

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

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))
[show source]
    # File lib/sequel/dataset/query.rb
643 def lateral
644   cached_dataset(:_lateral_ds){clone(:lateral=>true)}
645 end
limit(l, o = (no_offset = true; nil))

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
[show source]
    # File lib/sequel/dataset/query.rb
657 def limit(l, o = (no_offset = true; nil))
658   return from_self.limit(l, o) if @opts[:sql]
659 
660   if l.is_a?(Range)
661     no_offset = false
662     o = l.first
663     l = l.last - l.first + (l.exclude_end? ? 0 : 1)
664   end
665   l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
666   if l.is_a?(Integer)
667     raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
668   end
669 
670   ds = clone(:limit=>l)
671   ds = ds.offset(o) unless no_offset
672   ds
673 end
lock_style(style)

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
[show source]
    # File lib/sequel/dataset/query.rb
687 def lock_style(style)
688   clone(:lock => style)
689 end
merge_delete(&block)

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
[show source]
    # File lib/sequel/dataset/query.rb
700 def merge_delete(&block)
701   _merge_when(:type=>:delete, &block)
702 end
merge_insert(*values, &block)

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))
[show source]
    # File lib/sequel/dataset/query.rb
716 def merge_insert(*values, &block)
717   _merge_when(:type=>:insert, :values=>values, &block)
718 end
merge_update(values, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
729 def merge_update(values, &block)
730   _merge_when(:type=>:update, :values=>values, &block)
731 end
merge_using(source, join_condition)

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)
[show source]
    # File lib/sequel/dataset/query.rb
737 def merge_using(source, join_condition)
738   clone(:merge_using => [source, join_condition].freeze)
739 end
naked()

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}]
[show source]
    # File lib/sequel/dataset/query.rb
746 def naked
747   cached_dataset(:_naked_ds){with_row_proc(nil)}
748 end
nowait()

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
[show source]
    # File lib/sequel/dataset/query.rb
755 def nowait
756   cached_dataset(:_nowait_ds) do
757     raise(Error, 'This dataset does not support raises errors instead of waiting for locked rows') unless supports_nowait?
758     clone(:nowait=>true)
759   end
760 end
offset(o)

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
[show source]
    # File lib/sequel/dataset/query.rb
767 def offset(o)
768   o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
769   if o.is_a?(Integer)
770     raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
771   end
772   clone(:offset => o)
773 end
or(*cond, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
781 def or(*cond, &block)
782   if @opts[:where].nil?
783     self
784   else
785     add_filter(:where, cond, false, :OR, &block)
786   end
787 end
order(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
803 def order(*columns, &block)
804   virtual_row_columns(columns, block)
805   clone(:order => (columns.compact.empty?) ? nil : columns.freeze)
806 end
order_append(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
813 def order_append(*columns, &block)
814   columns = @opts[:order] + columns if @opts[:order]
815   order(*columns, &block)
816 end
order_by(*columns, &block)

Alias of order

[show source]
    # File lib/sequel/dataset/query.rb
819 def order_by(*columns, &block)
820   order(*columns, &block)
821 end
order_more(*columns, &block)

Alias of order_append.

[show source]
    # File lib/sequel/dataset/query.rb
824 def order_more(*columns, &block)
825   order_append(*columns, &block)
826 end
order_prepend(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
833 def order_prepend(*columns, &block)
834   ds = order(*columns, &block)
835   @opts[:order] ? ds.order_append(*@opts[:order]) : ds
836 end
qualify(table=(cache=true; first_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)
[show source]
    # File lib/sequel/dataset/query.rb
845 def qualify(table=(cache=true; first_source))
846   o = @opts
847   return self if o[:sql]
848 
849   pr = proc do
850     h = {}
851     (o.keys & QUALIFY_KEYS).each do |k|
852       h[k] = qualified_expression(o[k], table)
853     end
854     h[:select] = [SQL::ColumnAll.new(table)].freeze if !o[:select] || o[:select].empty?
855     clone(h)
856   end
857 
858   cache ? cached_dataset(:_qualify_ds, &pr) : pr.call
859 end
returning(*values)

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
[show source]
    # File lib/sequel/dataset/query.rb
879 def returning(*values)
880   if values.empty?
881     cached_dataset(:_returning_ds) do
882       raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
883       clone(:returning=>EMPTY_ARRAY)
884     end
885   else
886     raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
887     clone(:returning=>values.freeze)
888   end
889 end
reverse(*order, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
898 def reverse(*order, &block)
899   if order.empty? && !block
900     cached_dataset(:_reverse_ds){order(*invert_order(@opts[:order]))}
901   else
902     virtual_row_columns(order, block)
903     order(*invert_order(order.empty? ? @opts[:order] : order.freeze))
904   end
905 end
reverse_order(*order, &block)

Alias of reverse

[show source]
    # File lib/sequel/dataset/query.rb
908 def reverse_order(*order, &block)
909   reverse(*order, &block)
910 end
select(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
919 def select(*columns, &block)
920   virtual_row_columns(columns, block)
921   clone(:select => columns.freeze)
922 end
select_all(*tables)

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
[show source]
    # File lib/sequel/dataset/query.rb
931 def select_all(*tables)
932   if tables.empty?
933     cached_dataset(:_select_all_ds){clone(:select => nil)}
934   else
935     select(*tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze)
936   end
937 end
select_append(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
946 def select_append(*columns, &block)
947   cur_sel = @opts[:select]
948   if !cur_sel || cur_sel.empty?
949     unless supports_select_all_and_column?
950       return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_append(*columns, &block)
951     end
952     cur_sel = [WILDCARD]
953   end
954   select(*(cur_sel + columns), &block)
955 end
select_group(*columns, &block)

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)
[show source]
    # File lib/sequel/dataset/query.rb
966 def select_group(*columns, &block)
967   virtual_row_columns(columns, block)
968   select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
969 end
select_more(*columns, &block)

Alias for select_append.

[show source]
    # File lib/sequel/dataset/query.rb
972 def select_more(*columns, &block)
973   select_append(*columns, &block)
974 end
server(servr)

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
[show source]
    # File lib/sequel/dataset/query.rb
985 def server(servr)
986   clone(:server=>servr)
987 end
server?(server)

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.

[show source]
    # File lib/sequel/dataset/query.rb
992 def server?(server)
993   if db.sharded? && !opts[:server]
994     server(server)
995   else
996     self
997   end
998 end
skip_limit_check()

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

[show source]
     # File lib/sequel/dataset/query.rb
1001 def skip_limit_check
1002   cached_dataset(:_skip_limit_check_ds) do
1003     clone(:skip_limit_check=>true)
1004   end
1005 end
skip_locked()

Skip locked rows when returning results from this dataset.

[show source]
     # File lib/sequel/dataset/query.rb
1008 def skip_locked
1009   cached_dataset(:_skip_locked_ds) do
1010     raise(Error, 'This dataset does not support skipping locked rows') unless supports_skip_locked?
1011     clone(:skip_locked=>true)
1012   end
1013 end
unfiltered()

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
[show source]
     # File lib/sequel/dataset/query.rb
1019 def unfiltered
1020   cached_dataset(:_unfiltered_ds){clone(:where => nil, :having => nil)}
1021 end
ungrouped()

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
[show source]
     # File lib/sequel/dataset/query.rb
1027 def ungrouped
1028   cached_dataset(:_ungrouped_ds){clone(:group => nil, :having => nil)}
1029 end
union(dataset, opts=OPTS)

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
[show source]
     # File lib/sequel/dataset/query.rb
1047 def union(dataset, opts=OPTS)
1048   compound_clone(:union, dataset, opts)
1049 end
unlimited()

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

DB[:items].limit(10, 20).unlimited # SELECT * FROM items
[show source]
     # File lib/sequel/dataset/query.rb
1054 def unlimited
1055   cached_dataset(:_unlimited_ds){clone(:limit=>nil, :offset=>nil)}
1056 end
unordered()

Returns a copy of the dataset with no order.

DB[:items].order(:a).unordered # SELECT * FROM items
[show source]
     # File lib/sequel/dataset/query.rb
1061 def unordered
1062   cached_dataset(:_unordered_ds){clone(:order=>nil)}
1063 end
where(*cond, &block)

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.

[show source]
     # File lib/sequel/dataset/query.rb
1107 def where(*cond, &block)
1108   add_filter(:where, cond, &block)
1109 end
window(name, opts)

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)
[show source]
     # File lib/sequel/dataset/query.rb
1117 def window(name, opts)
1118   clone(:window=>((@opts[:window]||EMPTY_ARRAY) + [[name, SQL::Window.new(opts)].freeze]).freeze)
1119 end
with(name, dataset, opts=OPTS)

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
[show source]
     # File lib/sequel/dataset/query.rb
1132 def with(name, dataset, opts=OPTS)
1133   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1134   if hoist_cte?(dataset)
1135     s, ds = hoist_cte(dataset)
1136     s.with(name, ds, opts)
1137   else
1138     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:name=>name, :dataset=>dataset)]).freeze)
1139   end
1140 end
with_extend(*mods, &block)

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.

[show source]
     # File lib/sequel/dataset/query.rb
1221 def with_extend(*mods, &block)
1222   c = Class.new(self.class)
1223   c.include(*mods) unless mods.empty?
1224   c.include(DatasetModule.new(&block)) if block
1225   o = c.freeze.allocate
1226   o.instance_variable_set(:@db, @db)
1227   o.instance_variable_set(:@opts, @opts)
1228   o.instance_variable_set(:@cache, {})
1229   if cols = cache_get(:_columns)
1230     o.send(:columns=, cols)
1231   end
1232   o.freeze
1233 end
with_recursive(name, nonrecursive, recursive, opts=OPTS)

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
[show source]
     # File lib/sequel/dataset/query.rb
1198 def with_recursive(name, nonrecursive, recursive, opts=OPTS)
1199   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1200   if hoist_cte?(nonrecursive)
1201     s, ds = hoist_cte(nonrecursive)
1202     s.with_recursive(name, ds, recursive, opts)
1203   elsif hoist_cte?(recursive)
1204     s, ds = hoist_cte(recursive)
1205     s.with_recursive(name, nonrecursive, ds, opts)
1206   else
1207     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)
1208   end
1209 end
with_row_proc(callable)

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}]
[show source]
     # File lib/sequel/dataset/query.rb
1250 def with_row_proc(callable)
1251   clone(:row_proc=>callable)
1252 end
with_sql(sql, *args)

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)

[show source]
     # File lib/sequel/dataset/query.rb
1284 def with_sql(sql, *args)
1285   if sql.is_a?(Symbol)
1286     sql = public_send(sql, *args)
1287   else
1288     sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
1289   end
1290   clone(:sql=>sql)
1291 end

Protected Instance methods

compound_clone(type, dataset, opts)

Add the dataset to the list of compounds

[show source]
     # File lib/sequel/dataset/query.rb
1296 def compound_clone(type, dataset, opts)
1297   if dataset.is_a?(Dataset) && dataset.opts[:with] && !supports_cte_in_compounds?
1298     s, ds = hoist_cte(dataset)
1299     return s.compound_clone(type, ds, opts)
1300   end
1301   ds = compound_from_self.clone(:compounds=>(Array(@opts[:compounds]).map(&:dup) + [[type, dataset.compound_from_self, opts[:all]].freeze]).freeze)
1302   opts[:from_self] == false ? ds : ds.from_self(opts)
1303 end
options_overlap(opts)

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

[show source]
     # File lib/sequel/dataset/query.rb
1306 def options_overlap(opts)
1307   !(@opts.map{|k,v| k unless v.nil?}.compact & opts).empty?
1308 end
simple_select_all?()

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

SELECT * FROM table
SELECT table.* FROM table
[show source]
     # File lib/sequel/dataset/query.rb
1317 def simple_select_all?
1318   return false unless (f = @opts[:from]) && f.length == 1
1319   o = @opts.reject{|k,v| v.nil? || non_sql_option?(k)}
1320   from = f.first
1321   from = from.expression if from.is_a?(SQL::AliasedExpression)
1322 
1323   if SIMPLE_SELECT_ALL_ALLOWED_FROM.any?{|x| from.is_a?(x)}
1324     case o.length
1325     when 1
1326       true
1327     when 2
1328       (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
1329     else
1330       false
1331     end
1332   else
1333     false
1334   end
1335 end

2 - Methods that execute code on the database

Constants

ACTION_METHODS = (<<-METHS).split.map(&:to_sym).freeze  

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

COLUMNS_CLONE_OPTIONS = {:distinct => nil, :limit => 0, :offset=>nil, :where=>nil, :having=>nil, :order=>nil, :row_proc=>nil, :graph=>nil, :eager_graph=>nil}.freeze  

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

COUNT_SELECT = Sequel.function(:count).*.as(:count)  
EMPTY_SELECT = Sequel::SQL::AliasedExpression.new(1, :one)  

Public Instance Aliases

with_sql_update -> with_sql_delete

Public Instance methods

<<(arg)

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)
[show source]
   # File lib/sequel/dataset/actions.rb
28 def <<(arg)
29   insert(arg)
30   self
31 end
[](*conditions)

Returns the first record matching the conditions. Examples:

DB[:table][id: 1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=>1}
[show source]
   # 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)

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}
[show source]
   # 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)

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.

[show source]
    # 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)

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
[show source]
   # 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()

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]
[show source]
   # File lib/sequel/dataset/actions.rb
75 def columns
76   _columns || columns!
77 end
columns!()

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

DB[:table].columns!
# => [:id, :name]
[show source]
   # 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)

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
[show source]
    # 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)

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))
[show source]
    # 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()

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.

[show source]
    # 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?()

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

DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1
# => false
[show source]
    # 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)

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}]
[show source]
    # 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)

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

[show source]
    # 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)

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']
[show source]
    # 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)

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.

[show source]
    # 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)

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
[show source]
    # 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)

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}]
[show source]
    # 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)

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'], ...]
[show source]
    # 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)

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
[show source]
    # 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()

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

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

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
[show source]
    # 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)

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.

[show source]
    # 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)

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
# ...
[show source]
    # 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)

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.

[show source]
    # 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)

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.

[show source]
    # 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)

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.

[show source]
    # 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)

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.

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

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'}
[show source]
    # File lib/sequel/dataset/actions.rb
769 def single_record
770   _single_record_ds.single_record!
771 end
single_record!()

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'}
[show source]
    # File lib/sequel/dataset/actions.rb
781 def single_record!
782   with_sql_first(select_sql)
783 end
single_value()

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'
[show source]
    # 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!()

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'
[show source]
    # 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)

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
[show source]
    # 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)

Alias of as_hash for backwards compatibility.

[show source]
    # 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)

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.

[show source]
    # 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()

Truncates the dataset. Returns nil.

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

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))
[show source]
    # 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)

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))
[show source]
    # 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)

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))
[show source]
    # 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)

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
[show source]
     # 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)

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.

[show source]
     # 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)

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.

[show source]
     # File lib/sequel/dataset/actions.rb
1022 def with_sql_delete(sql)
1023   execute_dui(sql)
1024 end
with_sql_each(sql)

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

[show source]
     # 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)

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

[show source]
     # 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)

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

[show source]
     # File lib/sequel/dataset/actions.rb
1055 def with_sql_insert(sql)
1056   execute_insert(sql)
1057 end
with_sql_single_value(sql)

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.

[show source]
     # 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

Protected Instance methods

_import(columns, values, opts)

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.

[show source]
     # 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)

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

[show source]
     # 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()

Returns an array of the first value in each row.

[show source]
     # 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()

A dataset for returning single values from the current dataset.

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

3 - User Methods relating to SQL Creation

Public Instance methods

exists()

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))
[show source]
   # File lib/sequel/dataset/sql.rb
14 def exists
15   SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
16 end
insert_sql(*values)

Returns an INSERT SQL query string. See insert.

DB[:items].insert_sql(a: 1)
# => "INSERT INTO items (a) VALUES (1)"
[show source]
   # 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)

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

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

[show source]
   # 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)

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).

[show source]
    # 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()

The SQL to use for the MERGE statement.

[show source]
    # 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)

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.

[show source]
    # 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()

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

[show source]
    # File lib/sequel/dataset/sql.rb
176 def sql
177   select_sql
178 end
truncate_sql()

Returns a TRUNCATE SQL query string. See truncate

DB[:items].truncate_sql # => 'TRUNCATE items'
[show source]
    # 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)

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.

[show source]
    # 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

Public Instance methods

provides_accurate_rows_matched?()

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.

[show source]
   # File lib/sequel/dataset/features.rb
19 def provides_accurate_rows_matched?
20   true
21 end
quote_identifiers?()

Whether this dataset quotes identifiers.

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

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

[show source]
   # File lib/sequel/dataset/features.rb
24 def recursive_cte_requires_column_aliases?
25   false
26 end
requires_placeholder_type_specifiers?()

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

[show source]
   # File lib/sequel/dataset/features.rb
41 def requires_placeholder_type_specifiers?
42   false
43 end
requires_sql_standard_datetimes?()

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.

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

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.

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

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.

[show source]
   # File lib/sequel/dataset/features.rb
55 def supports_cte_in_subqueries?
56   false
57 end
supports_deleting_joins?()

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

[show source]
   # File lib/sequel/dataset/features.rb
60 def supports_deleting_joins?
61   supports_modifying_joins?
62 end
supports_derived_column_lists?()

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

[show source]
   # File lib/sequel/dataset/features.rb
67 def supports_derived_column_lists?
68   true
69 end
supports_distinct_on?()

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

[show source]
   # File lib/sequel/dataset/features.rb
72 def supports_distinct_on?
73   false
74 end
supports_group_cube?()

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

[show source]
   # File lib/sequel/dataset/features.rb
77 def supports_group_cube?
78   false
79 end
supports_group_rollup?()

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

[show source]
   # File lib/sequel/dataset/features.rb
82 def supports_group_rollup?
83   false
84 end
supports_grouping_sets?()

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

[show source]
   # File lib/sequel/dataset/features.rb
87 def supports_grouping_sets?
88   false
89 end
supports_insert_select?()

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

[show source]
   # File lib/sequel/dataset/features.rb
93 def supports_insert_select?
94   supports_returning?(:insert)
95 end
supports_intersect_except?()

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

[show source]
    # File lib/sequel/dataset/features.rb
 98 def supports_intersect_except?
 99   true
100 end
supports_intersect_except_all?()

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

[show source]
    # File lib/sequel/dataset/features.rb
103 def supports_intersect_except_all?
104   true
105 end
supports_is_true?()

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

[show source]
    # File lib/sequel/dataset/features.rb
108 def supports_is_true?
109   true
110 end
supports_join_using?()

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).

[show source]
    # File lib/sequel/dataset/features.rb
114 def supports_join_using?
115   true
116 end
supports_lateral_subqueries?()

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

[show source]
    # File lib/sequel/dataset/features.rb
119 def supports_lateral_subqueries?
120   false
121 end
supports_limits_in_correlated_subqueries?()

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

[show source]
    # File lib/sequel/dataset/features.rb
124 def supports_limits_in_correlated_subqueries?
125   true
126 end
supports_merge?()

Whether the MERGE statement is supported, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
134 def supports_merge?
135   false
136 end
supports_modifying_joins?()

Whether modifying joined datasets is supported, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
139 def supports_modifying_joins?
140   false
141 end
supports_multiple_column_in?()

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

[show source]
    # File lib/sequel/dataset/features.rb
145 def supports_multiple_column_in?
146   true
147 end
supports_nowait?()

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

[show source]
    # File lib/sequel/dataset/features.rb
129 def supports_nowait?
130   false
131 end
supports_offsets_in_correlated_subqueries?()

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

[show source]
    # File lib/sequel/dataset/features.rb
150 def supports_offsets_in_correlated_subqueries?
151   true
152 end
supports_ordered_distinct_on?()

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

[show source]
    # File lib/sequel/dataset/features.rb
156 def supports_ordered_distinct_on?
157   supports_distinct_on?
158 end
supports_placeholder_literalizer?()

Whether placeholder literalizers are supported, true by default.

[show source]
    # File lib/sequel/dataset/features.rb
161 def supports_placeholder_literalizer?
162   true
163 end
supports_regexp?()

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

[show source]
    # File lib/sequel/dataset/features.rb
166 def supports_regexp?
167   false
168 end
supports_replace?()

Whether the dataset supports REPLACE syntax, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
171 def supports_replace?
172   false
173 end
supports_returning?(type)

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

[show source]
    # File lib/sequel/dataset/features.rb
177 def supports_returning?(type)
178   false
179 end
supports_select_all_and_column?()

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

[show source]
    # File lib/sequel/dataset/features.rb
187 def supports_select_all_and_column?
188   true
189 end
supports_skip_locked?()

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

[show source]
    # File lib/sequel/dataset/features.rb
182 def supports_skip_locked?
183   false
184 end
supports_timestamp_timezones?()

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

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

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

[show source]
    # File lib/sequel/dataset/features.rb
201 def supports_timestamp_usecs?
202   true
203 end
supports_updating_joins?()

Whether updating joined datasets is supported, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
206 def supports_updating_joins?
207   supports_modifying_joins?
208 end
supports_where_true?()

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

[show source]
    # File lib/sequel/dataset/features.rb
235 def supports_where_true?
236   true
237 end
supports_window_clause?()

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

[show source]
    # File lib/sequel/dataset/features.rb
212 def supports_window_clause?
213   false
214 end
supports_window_function_frame_option?(option)

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.

[show source]
    # 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?()

Whether the dataset supports window functions, false by default.

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

5 - Methods related to dataset graphing

Public Instance methods

add_graph_aliases(graph_aliases)

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
[show source]
   # 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)

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.

[show source]
    # 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)

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 ...
[show source]
    # 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()

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

[show source]
    # File lib/sequel/dataset/graph.rb
255 def ungraphed
256   clone(:graph=>nil)
257 end

6 - Miscellaneous methods

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)

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.

[show source]
   # 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)

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

[show source]
   # 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()

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

[show source]
   # File lib/sequel/dataset/misc.rb
40 def current_datetime
41   Sequel.datetime_class.now
42 end
dup()

Return self, as datasets are always frozen.

[show source]
   # File lib/sequel/dataset/misc.rb
50 def dup
51   self
52 end
each_server()

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')}
[show source]
   # File lib/sequel/dataset/misc.rb
59 def each_server
60   db.servers.each{|s| yield server(s)}
61 end
eql?(o)

Alias for ==

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

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

Alias of first_source_alias

[show source]
   # File lib/sequel/dataset/misc.rb
91 def first_source
92   first_source_alias
93 end
first_source_alias()

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
[show source]
    # 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()

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
[show source]
    # 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()

Freeze the opts when freezing the dataset.

[show source]
   # File lib/sequel/dataset/misc.rb
74 def freeze
75   @opts.freeze
76   super
77 end
hash()

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

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

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

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

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

[show source]
    # 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()

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

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

A placeholder literalizer loader for the current dataset.

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

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

[show source]
    # File lib/sequel/dataset/misc.rb
173 def row_number_column
174   :x_sequel_row_number_x
175 end
row_proc()

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.

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

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.

[show source]
    # 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)

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.

[show source]
    # 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 = [])

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
[show source]
    # 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)

Return a modified dataset with quote_identifiers set.

[show source]
    # 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()

The cached columns for the current dataset.

[show source]
    # File lib/sequel/dataset/misc.rb
281 def _columns
282   cache_get(:_columns)
283 end
cache_get(k)

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

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

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

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

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).

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

8 - Methods related to prepared statements or bound variables

Constants

DEFAULT_PREPARED_STATEMENT_MODULE_METHODS = %w'execute execute_dui execute_insert'.freeze.each(&:freeze)  
PREPARED_ARG_PLACEHOLDER = LiteralString.new('?').freeze  
PREPARED_STATEMENT_MODULE_CODE = { :bind => "opts = Hash[opts]; opts[:arguments] = bind_arguments".freeze, :prepare => "sql = prepared_statement_name".freeze, :prepare_bind => "sql = prepared_statement_name; opts = Hash[opts]; opts[:arguments] = bind_arguments".freeze }.freeze  

Public Instance methods

bind(bind_vars=OPTS)

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}
[show source]
    # 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)

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}
[show source]
    # 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)

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
[show source]
    # 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)

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

[show source]
    # 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

9 - Internal Methods relating to SQL Creation

Constants

BITWISE_METHOD_MAP = {:& =>:BITAND, :| => :BITOR, :^ => :BITXOR}.freeze  
COUNT_FROM_SELF_OPTS = [:distinct, :group, :sql, :limit, :offset, :compounds].freeze  
COUNT_OF_ALL_AS_COUNT = SQL::Function.new(:count, WILDCARD).as(:count)  
DEFAULT = LiteralString.new('DEFAULT').freeze  
EXISTS = ['EXISTS '.freeze].freeze  
IS_LITERALS = {nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze  
IS_OPERATORS = ::Sequel::SQL::ComplexExpression::IS_OPERATORS  
LIKE_OPERATORS = ::Sequel::SQL::ComplexExpression::LIKE_OPERATORS  
N_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS  
QUALIFY_KEYS = [:select, :where, :having, :order, :group].freeze  
REGEXP_OPERATORS = ::Sequel::SQL::ComplexExpression::REGEXP_OPERATORS  
TWO_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS  
WILDCARD = LiteralString.new('*').freeze  

Public Class methods

clause_methods(type, clauses)

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

[show source]
    # 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)

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.

[show source]
    # 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)

Append literalization of aliased expression to SQL string.

[show source]
    # 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)

Append literalization of array to SQL string.

[show source]
    # 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)

Append literalization of boolean constant to SQL string.

[show source]
    # 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)

Append literalization of case expression to SQL string.

[show source]
    # 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)

Append literalization of cast expression to SQL string.

[show source]
    # 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)

Append literalization of column all selection to SQL string.

[show source]
    # 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)

Append literalization of complex expression to SQL string.

[show source]
    # 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)

Append literalization of constant to SQL string.

[show source]
    # 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)

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

[show source]
    # 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)

Append literalization of function call to SQL string.

[show source]
    # 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)

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

[show source]
    # 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)

Append literalization of JOIN ON clause to SQL string.

[show source]
    # 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)

Append literalization of JOIN USING clause to SQL string.

[show source]
    # 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)

Append literalization of negative boolean constant to SQL string.

[show source]
    # 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)

Append literalization of ordered expression to SQL string.

[show source]
    # 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)

Append literalization of placeholder literal string to SQL string.

[show source]
    # 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))

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.

[show source]
    # 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)

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.

[show source]
    # 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)

Append literalization of identifier or unqualified identifier to SQL string.

[show source]
    # 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)

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).

[show source]
    # 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)

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).

[show source]
    # 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)

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']
[show source]
    # 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)

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

[show source]
    # 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)

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

[show source]
    # 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()

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

[show source]
    # 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