Class Sequel::Dataset
In: lib/sequel/dataset/features.rb
lib/sequel/dataset/prepared_statements.rb
lib/sequel/dataset/graph.rb
lib/sequel/dataset/mutation.rb
lib/sequel/dataset/misc.rb
lib/sequel/dataset/sql.rb
lib/sequel/dataset/query.rb
lib/sequel/dataset/actions.rb
lib/sequel/extensions/split_array_nil.rb
lib/sequel/extensions/null_dataset.rb
lib/sequel/extensions/pagination.rb
lib/sequel/extensions/query.rb
lib/sequel/adapters/swift.rb
lib/sequel/adapters/utils/stored_procedures.rb
lib/sequel/adapters/utils/replace.rb
lib/sequel/adapters/jdbc.rb
lib/sequel/adapters/mysql.rb
lib/sequel/adapters/do.rb
lib/sequel/adapters/sqlite.rb
lib/sequel/dataset.rb
Parent: Object

A dataset represents an SQL query, or more generally, an abstract set of rows in the database. Datasets can be used to create, retrieve, 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].filter(:author => 'david') # no records are retrieved
  my_posts.all # records are retrieved
  my_posts.all # records are retrieved again

Most dataset methods return modified copies of the dataset (functional style), so you can reuse different datasets to access data:

  posts = DB[:posts]
  davids_posts = posts.filter(:author => 'david')
  old_posts = posts.filter('stamp < ?', Date.today - 7)
  davids_old_posts = davids_posts.filter('stamp < ?', Date.today - 7)

Datasets are Enumerable objects, so they can be manipulated using any of the Enumerable methods, such as map, inject, etc.

For more information, see the "Dataset Basics" guide.

Methods

<<   ==   []   _import   _insert_sql   _select_map_multiple   _select_map_single   _update_sql   add_graph_aliases   aliased_expression_sql_append   all   and   array_sql_append   avg   bind   boolean_constant_sql_append   call   call   case_expression_sql_append   cast_sql_append   clause_methods   clone   column_all_sql_append   columns   columns!   complex_expression_sql_append   compound_clone   compound_from_self   constant_sql_append   count   def_mutation_method   delayed_evaluation_sql_append   delete   delete_sql   distinct   each   each_server   empty?   emulated_function_sql_append   eql?   escape_like   except   exclude   exclude_having   exclude_where   exists   extension   extension!   fetch_rows   fetch_rows   fetch_rows   fetch_rows   fetch_rows   filter   first   first!   first_source   first_source_alias   first_source_table   for_update   from   from_self   from_self!   function_sql_append   get   graph   graph   grep   group   group_and_count   group_by   group_cube   group_rollup   hash   having   identifier_input_method   identifier_output_method   import   insert   insert_sql   inspect   intersect   interval   invert   join   join_clause_sql_append   join_on_clause_sql_append   join_table   join_using_clause_sql_append   last   limit   literal_append   lock_style   map   max   min   multi_insert   multi_insert_sql   naked   naked!   negative_boolean_constant_sql_append   new   options_overlap   or   order   order_append   order_by   order_more   order_prepend   ordered_expression_sql_append   paged_each   placeholder_literal_string_sql_append   prepare   prepare   prepare   provides_accurate_rows_matched?   qualified_identifier_sql_append   qualify   quote_identifier_append   quote_identifiers?   quote_schema_table_append   quoted_identifier_append   range   recursive_cte_requires_column_aliases?   register_extension   requires_placeholder_type_specifiers?   requires_sql_standard_datetimes?   returning   reverse   reverse_order   row_number_column   schema_and_table   select   select_all   select_append   select_group   select_hash   select_hash_groups   select_map   select_more   select_order_map   select_sql   server   set_graph_aliases   simple_select_all?   single_record   single_value   split_alias   split_multiple_result_sets   split_qualifiers   sql   subscript_sql_append   sum   supports_cte?   supports_cte_in_subqueries?   supports_distinct_on?   supports_group_cube?   supports_group_rollup?   supports_insert_select?   supports_intersect_except?   supports_intersect_except_all?   supports_is_true?   supports_join_using?   supports_modifying_joins?   supports_multiple_column_in?   supports_ordered_distinct_on?   supports_regexp?   supports_replace?   supports_returning?   supports_select_all_and_column?   supports_timestamp_timezones?   supports_timestamp_usecs?   supports_where_true?   supports_window_functions?   to_hash   to_hash_groups   to_prepared_statement   truncate   truncate_sql   unbind   unfiltered   ungraphed   ungrouped   union   unlimited   unordered   unused_table_alias   update   update_sql   where   window_function_sql_append   window_sql_append   with   with_recursive   with_sql   with_sql_delete  

Included Modules

4 - Methods that describe what the dataset supports

These methods all return booleans, with most describing whether or not the dataset supports a feature.

Public Instance methods

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

[Source]

    # File lib/sequel/dataset/features.rb, line 21
21:     def provides_accurate_rows_matched?
22:       true
23:     end

Whether this dataset quotes identifiers.

[Source]

    # File lib/sequel/dataset/features.rb, line 10
10:     def quote_identifiers?
11:       if defined?(@quote_identifiers)
12:         @quote_identifiers
13:       else
14:         @quote_identifiers = db.quote_identifiers?
15:       end
16:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 27
27:     def recursive_cte_requires_column_aliases?
28:       false
29:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 39
39:     def requires_placeholder_type_specifiers?
40:       false
41:     end

Whether the dataset requires SQL standard datetimes (false by default, as most allow strings with ISO 8601 format).

[Source]

    # File lib/sequel/dataset/features.rb, line 33
33:     def requires_sql_standard_datetimes?
34:       false
35:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 46
46:     def supports_cte?(type=:select)
47:       send("#{type}_clause_methods""#{type}_clause_methods").include?("#{type}_with_sql""#{type}_with_sql")
48:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 53
53:     def supports_cte_in_subqueries?
54:       false
55:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 58
58:     def supports_distinct_on?
59:       false
60:     end

Whether the dataset supports CUBE with GROUP BY.

[Source]

    # File lib/sequel/dataset/features.rb, line 63
63:     def supports_group_cube?
64:       false
65:     end

Whether the dataset supports ROLLUP with GROUP BY.

[Source]

    # File lib/sequel/dataset/features.rb, line 68
68:     def supports_group_rollup?
69:       false
70:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 74
74:     def supports_insert_select?
75:       supports_returning?(:insert)
76:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 79
79:     def supports_intersect_except?
80:       true
81:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 84
84:     def supports_intersect_except_all?
85:       true
86:     end

Whether the dataset supports the IS TRUE syntax.

[Source]

    # File lib/sequel/dataset/features.rb, line 89
89:     def supports_is_true?
90:       true
91:     end

Whether the dataset supports the JOIN table USING (column1, …) syntax.

[Source]

    # File lib/sequel/dataset/features.rb, line 94
94:     def supports_join_using?
95:       true
96:     end

Whether modifying joined datasets is supported.

[Source]

     # File lib/sequel/dataset/features.rb, line 99
 99:     def supports_modifying_joins?
100:       false
101:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 105
105:     def supports_multiple_column_in?
106:       true
107:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 111
111:     def supports_ordered_distinct_on?
112:       supports_distinct_on?
113:     end

Whether the dataset supports pattern matching by regular expressions.

[Source]

     # File lib/sequel/dataset/features.rb, line 116
116:     def supports_regexp?
117:       false
118:     end

Whether the dataset supports REPLACE syntax, false by default.

[Source]

     # File lib/sequel/dataset/features.rb, line 121
121:     def supports_replace?
122:       false
123:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 127
127:     def supports_returning?(type)
128:       send("#{type}_clause_methods""#{type}_clause_methods").include?("#{type}_returning_sql""#{type}_returning_sql")
129:     end

Whether the database supports SELECT *, column FROM table

[Source]

     # File lib/sequel/dataset/features.rb, line 132
132:     def supports_select_all_and_column?
133:       true
134:     end

Whether the dataset supports timezones in literal timestamps

[Source]

     # File lib/sequel/dataset/features.rb, line 137
137:     def supports_timestamp_timezones?
138:       false
139:     end

Whether the dataset supports fractional seconds in literal timestamps

[Source]

     # File lib/sequel/dataset/features.rb, line 142
142:     def supports_timestamp_usecs?
143:       true
144:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 153
153:     def supports_where_true?
154:       true
155:     end

Whether the dataset supports window functions.

[Source]

     # File lib/sequel/dataset/features.rb, line 147
147:     def supports_window_functions?
148:       false
149:     end

8 - Methods related to prepared statements or bound variables

On some adapters, these use native prepared statements and bound variables, on others support is emulated. For details, see the "Prepared Statements/Bound Variables" guide.

Constants

PREPARED_ARG_PLACEHOLDER = LiteralString.new('?').freeze

Public Instance methods

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].filter(:id=>:$id).bind(:id=>1).call(:first)
  # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
  # => {:id=>1}

[Source]

     # File lib/sequel/dataset/prepared_statements.rb, line 219
219:     def bind(bind_vars={})
220:       clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars)
221:     end

For the given type (:select, :first, :insert, :insert_select, :update, or :delete), 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].filter(:id=>:$id).call(:first, :id=>1)
  # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
  # => {:id=>1}

[Source]

     # File lib/sequel/dataset/prepared_statements.rb, line 230
230:     def call(type, bind_variables={}, *values, &block)
231:       prepare(type, nil, *values).call(bind_variables, &block)
232:     end

Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement. While name defaults to nil, it should always be provided as a symbol for the name of the prepared statement, as some databases require that prepared statements have names.

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].filter(: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

[Source]

     # File lib/sequel/dataset/prepared_statements.rb, line 252
252:     def prepare(type, name=nil, *values)
253:       ps = to_prepared_statement(type, values)
254:       db.set_prepared_statement(name, ps) if name
255:       ps
256:     end

Protected Instance methods

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

[Source]

     # File lib/sequel/dataset/prepared_statements.rb, line 262
262:     def to_prepared_statement(type, values=nil)
263:       ps = bind
264:       ps.extend(PreparedStatementMethods)
265:       ps.orig_dataset = self
266:       ps.prepared_type = type
267:       ps.prepared_modify_values = values
268:       ps
269:     end

5 - Methods related to dataset graphing

Dataset graphing changes the dataset to yield hashes where keys are table name symbols and values are hashes representing the columns related to that table. All of these methods return modified copies of the receiver.

Public Instance methods

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_more when graphing). See set_graph_aliases.

  DB[:table].add_graph_aliases(:some_alias=>[:table, :column])
  # SELECT ..., table.column AS some_alias

[Source]

    # File lib/sequel/dataset/graph.rb, line 16
16:     def add_graph_aliases(graph_aliases)
17:       unless (ga = opts[:graph_aliases]) || (opts[:graph] && (ga = opts[:graph][:column_aliases]))
18:         raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases"
19:       end
20:       columns, graph_aliases = graph_alias_columns(graph_aliases)
21:       select_more(*columns).clone(:graph_aliases => ga.merge(graph_aliases))
22:     end

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 object that responds to dataset and returns a symbol or a dataset
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_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 the alias (or table) name is used more than once.

[Source]

     # File lib/sequel/dataset/graph.rb, line 49
 49:     def graph(dataset, join_conditions = nil, options = OPTS, &block)
 50:       # Allow the use of a dataset or symbol as the first argument
 51:       # Find the table name/dataset based on the argument
 52:       table_alias = options[:table_alias]
 53:       case dataset
 54:       when Symbol
 55:         table = dataset
 56:         dataset = @db[dataset]
 57:         table_alias ||= table
 58:       when ::Sequel::Dataset
 59:         if dataset.simple_select_all?
 60:           table = dataset.opts[:from].first
 61:           table_alias ||= table
 62:         else
 63:           table = dataset
 64:           table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
 65:         end
 66:       else
 67:         raise Error, "The dataset argument should be a symbol or dataset"
 68:       end
 69: 
 70:       # Raise Sequel::Error with explanation that the table alias has been used
 71:       raise_alias_error = lambda do
 72:         raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \
 73:           "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 
 74:       end
 75: 
 76:       # Only allow table aliases that haven't been used
 77:       raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
 78:       
 79:       # Use a from_self if this is already a joined table
 80:       ds = (!@opts[:graph] && (@opts[:from].length > 1 || @opts[:join])) ? from_self(:alias=>options[:from_self_alias] || first_source) : self
 81:       
 82:       # Join the table early in order to avoid cloning the dataset twice
 83:       ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>options[:implicit_qualifier], :qualify=>options[:qualify], &block)
 84:       opts = ds.opts
 85: 
 86:       # Whether to include the table in the result set
 87:       add_table = options[:select] == false ? false : true
 88:       # Whether to add the columns to the list of column aliases
 89:       add_columns = !ds.opts.include?(:graph_aliases)
 90: 
 91:       # Setup the initial graph data structure if it doesn't exist
 92:       if graph = opts[:graph]
 93:         opts[:graph] = graph = graph.dup
 94:         select = opts[:select].dup
 95:         [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
 96:       else
 97:         master = alias_symbol(ds.first_source_alias)
 98:         raise_alias_error.call if master == table_alias
 99:         # Master hash storing all .graph related information
100:         graph = opts[:graph] = {}
101:         # Associates column aliases back to tables and columns
102:         column_aliases = graph[:column_aliases] = {}
103:         # Associates table alias (the master is never aliased)
104:         table_aliases = graph[:table_aliases] = {master=>self}
105:         # Keep track of the alias numbers used
106:         ca_num = graph[:column_alias_num] = Hash.new(0)
107:         # All columns in the master table are never
108:         # aliased, but are not included if set_graph_aliases
109:         # has been used.
110:         if add_columns
111:           if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll)))
112:             select = select.each do |sel|
113:               column = case sel
114:               when Symbol
115:                 _, c, a = split_symbol(sel)
116:                 (a || c).to_sym
117:               when SQL::Identifier
118:                 sel.value.to_sym
119:               when SQL::QualifiedIdentifier
120:                 column = sel.column
121:                 column = column.value if column.is_a?(SQL::Identifier)
122:                 column.to_sym
123:               when SQL::AliasedExpression
124:                 column = sel.aliaz
125:                 column = column.value if column.is_a?(SQL::Identifier)
126:                 column.to_sym
127:               else
128:                 raise Error, "can't figure out alias to use for graphing for #{sel.inspect}"
129:               end
130:               column_aliases[column] = [master, column]
131:             end
132:             select = qualified_expression(select, master)
133:           else
134:             select = columns.map do |column|
135:               column_aliases[column] = [master, column]
136:               SQL::QualifiedIdentifier.new(master, column)
137:             end
138:           end
139:         end
140:       end
141: 
142:       # Add the table alias to the list of aliases
143:       # Even if it isn't been used in the result set,
144:       # we add a key for it with a nil value so we can check if it
145:       # is used more than once
146:       table_aliases = graph[:table_aliases]
147:       table_aliases[table_alias] = add_table ? dataset : nil
148: 
149:       # Add the columns to the selection unless we are ignoring them
150:       if add_table && add_columns
151:         column_aliases = graph[:column_aliases]
152:         ca_num = graph[:column_alias_num]
153:         # Which columns to add to the result set
154:         cols = options[:select] || dataset.columns
155:         # If the column hasn't been used yet, don't alias it.
156:         # If it has been used, try table_column.
157:         # If that has been used, try table_column_N 
158:         # using the next value of N that we know hasn't been
159:         # used
160:         cols.each do |column|
161:           col_alias, identifier = if column_aliases[column]
162:             column_alias = "#{table_alias}_#{column}""#{table_alias}_#{column}"
163:             if column_aliases[column_alias]
164:               column_alias_num = ca_num[column_alias]
165:               column_alias = "#{column_alias}_#{column_alias_num}""#{column_alias}_#{column_alias_num}" 
166:               ca_num[column_alias] += 1
167:             end
168:             [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias, column), column_alias)]
169:           else
170:             ident = SQL::QualifiedIdentifier.new(table_alias, column)
171:             [column, ident]
172:           end
173:           column_aliases[col_alias] = [table_alias, column]
174:           select.push(identifier)
175:         end
176:       end
177:       add_columns ? ds.select(*select) : ds
178:     end

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 ...

[Source]

     # File lib/sequel/dataset/graph.rb, line 203
203:     def set_graph_aliases(graph_aliases)
204:       columns, graph_aliases = graph_alias_columns(graph_aliases)
205:       ds = select(*columns)
206:       ds.opts[:graph_aliases] = graph_aliases
207:       ds
208:     end

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

[Source]

     # File lib/sequel/dataset/graph.rb, line 212
212:     def ungraphed
213:       clone(:graph=>nil, :graph_aliases=>nil)
214:     end

7 - Mutation methods

These methods modify the receiving dataset and should be used with care.

Constants

MUTATION_METHODS = QUERY_METHODS - [:paginate, :naked, :from_self]   All methods that should have a ! method added that modifies the receiver.

Attributes

identifier_input_method  [W]  Set the method to call on identifiers going into the database for this dataset
identifier_output_method  [W]  Set the method to call on identifiers coming the database for this dataset
quote_identifiers  [W]  Whether to quote identifiers for this dataset
row_proc  [RW]  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.

Public Class methods

Setup mutation (e.g. filter!) methods. These operate the same as the non-! methods, but replace the options of the current dataset with the options of the resulting dataset.

Do not call this method with untrusted input, as that can result in arbitrary code execution.

[Source]

    # File lib/sequel/dataset/mutation.rb, line 17
17:     def self.def_mutation_method(*meths)
18:       options = meths.pop if meths.last.is_a?(Hash)
19:       mod = options[:module] if options
20:       mod ||= self
21:       meths.each do |meth|
22:         mod.class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__)
23:       end
24:     end

Public Instance methods

Load an extension into the receiver. In addition to requiring the extension file, this also modifies the dataset to work with the extension (usually extending it with a module defined in the extension file). If no related extension file exists or the extension does not have specific support for Database objects, an Error will be raised. Returns self.

[Source]

    # File lib/sequel/dataset/mutation.rb, line 47
47:     def extension!(*exts)
48:       Sequel.extension(*exts)
49:       exts.each do |ext|
50:         if pr = Sequel.synchronize{EXTENSIONS[ext]}
51:           pr.call(self)
52:         else
53:           raise(Error, "Extension #{ext} does not have specific support handling individual datasets")
54:         end
55:       end
56:       self
57:     end

Avoid self-referential dataset by cloning.

[Source]

    # File lib/sequel/dataset/mutation.rb, line 60
60:     def from_self!(*args, &block)
61:       @opts = clone.from_self(*args, &block).opts
62:       self
63:     end

Remove the row_proc from the current dataset.

[Source]

    # File lib/sequel/dataset/mutation.rb, line 66
66:     def naked!
67:       self.row_proc = nil
68:       self
69:     end

6 - Miscellaneous methods

These methods don‘t fit cleanly into another section.

Constants

NOTIMPL_MSG = "This method must be overridden in Sequel adapters".freeze
ARRAY_ACCESS_ERROR_MSG = 'You cannot call Dataset#[] with an integer or with no arguments.'.freeze
ARG_BLOCK_ERROR_MSG = 'Must use either an argument or a block, not both'.freeze
IMPORT_ERROR_MSG = 'Using Sequel::Dataset#import an empty column array is not allowed'.freeze

Attributes

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

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.

[Source]

    # File lib/sequel/dataset/misc.rb, line 28
28:     def initialize(db)
29:       @db = db
30:       @opts = OPTS
31:     end

Public Instance methods

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

[Source]

    # File lib/sequel/dataset/misc.rb, line 35
35:     def ==(o)
36:       o.is_a?(self.class) && db == o.db && opts == o.opts && sql == o.sql
37:     end

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')}

[Source]

    # File lib/sequel/dataset/misc.rb, line 49
49:     def each_server
50:       db.servers.each{|s| yield server(s)}
51:     end

Alias for ==

[Source]

    # File lib/sequel/dataset/misc.rb, line 40
40:     def eql?(o)
41:       self == o
42:     end

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\\\%\_'

[Source]

    # File lib/sequel/dataset/misc.rb, line 58
58:     def escape_like(string)
59:       string.gsub(/[\\%_]/){|m| "\\#{m}"}
60:     end

Alias of first_source_alias

[Source]

    # File lib/sequel/dataset/misc.rb, line 63
63:     def first_source
64:       first_source_alias
65:     end

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[:table___t].first_source_alias
  # => :t

[Source]

    # File lib/sequel/dataset/misc.rb, line 75
75:     def first_source_alias
76:       source = @opts[:from]
77:       if source.nil? || source.empty?
78:         raise Error, 'No source specified for query'
79:       end
80:       case s = source.first
81:       when SQL::AliasedExpression
82:         s.aliaz
83:       when Symbol
84:         _, _, aliaz = split_symbol(s)
85:         aliaz ? aliaz.to_sym : s
86:       else
87:         s
88:       end
89:     end

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[:table___t].first_source_table
  # => :table

[Source]

     # File lib/sequel/dataset/misc.rb, line 100
100:     def first_source_table
101:       source = @opts[:from]
102:       if source.nil? || source.empty?
103:         raise Error, 'No source specified for query'
104:       end
105:       case s = source.first
106:       when SQL::AliasedExpression
107:         s.expression
108:       when Symbol
109:         sch, table, aliaz = split_symbol(s)
110:         aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
111:       else
112:         s
113:       end
114:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 118
118:     def hash
119:       [db, opts, sql].hash
120:     end

The String instance method to call on identifiers before sending them to the database.

[Source]

     # File lib/sequel/dataset/misc.rb, line 124
124:     def identifier_input_method
125:       if defined?(@identifier_input_method)
126:         @identifier_input_method
127:       else
128:         @identifier_input_method = db.identifier_input_method
129:       end
130:     end

The String instance method to call on identifiers before sending them to the database.

[Source]

     # File lib/sequel/dataset/misc.rb, line 134
134:     def identifier_output_method
135:       if defined?(@identifier_output_method)
136:         @identifier_output_method
137:       else
138:         @identifier_output_method = db.identifier_output_method
139:       end
140:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 144
144:     def inspect
145:       c = self.class
146:       c = c.superclass while c.name.nil? || c.name == ''
147:       "#<#{c.name}: #{sql.inspect}>"
148:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 152
152:     def row_number_column
153:       :x_sequel_row_number_x
154:     end

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.

[Source]

     # File lib/sequel/dataset/misc.rb, line 159
159:     def split_alias(c)
160:       case c
161:       when Symbol
162:         c_table, column, aliaz = split_symbol(c)
163:         [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
164:       when SQL::AliasedExpression
165:         [c.expression, c.aliaz]
166:       when SQL::JoinClause
167:         [c.table, c.table_alias]
168:       else
169:         [c, nil]
170:       end
171:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 195
195:     def unused_table_alias(table_alias, used_aliases = [])
196:       table_alias = alias_symbol(table_alias)
197:       used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
198:       used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
199:       if used_aliases.include?(table_alias)
200:         i = 0
201:         loop do
202:           ta = "#{table_alias}_#{i}""#{table_alias}_#{i}"
203:           return ta unless used_aliases.include?(ta)
204:           i += 1 
205:         end
206:       else
207:         table_alias
208:       end
209:     end

3 - User Methods relating to SQL Creation

These are methods you can call to see what SQL will be generated by the dataset.

Public Instance methods

Returns a DELETE SQL query string. See delete.

  dataset.filter{|o| o.price >= 100}.delete_sql
  # => "DELETE FROM items WHERE (price >= 100)"

[Source]

    # File lib/sequel/dataset/sql.rb, line 12
12:     def delete_sql
13:       return static_sql(opts[:sql]) if opts[:sql]
14:       check_modification_allowed!
15:       clause_sql(:delete)
16:     end

Returns an EXISTS clause for the dataset as a LiteralString.

  DB.select(1).where(DB[:items].exists)
  # SELECT 1 WHERE (EXISTS (SELECT * FROM items))

[Source]

    # File lib/sequel/dataset/sql.rb, line 22
22:     def exists
23:       SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
24:     end

Returns an INSERT SQL query string. See insert.

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

[Source]

    # File lib/sequel/dataset/sql.rb, line 30
30:     def insert_sql(*values)
31:       return static_sql(@opts[:sql]) if @opts[:sql]
32: 
33:       check_modification_allowed!
34: 
35:       columns = []
36: 
37:       case values.size
38:       when 0
39:         return insert_sql({})
40:       when 1
41:         case vals = values.at(0)
42:         when Hash
43:           values = []
44:           vals.each do |k,v| 
45:             columns << k
46:             values << v
47:           end
48:         when Dataset, Array, LiteralString
49:           values = vals
50:         end
51:       when 2
52:         if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
53:           columns, values = v0, v1
54:           raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
55:         end
56:       end
57: 
58:       if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
59:         columns = [columns().last]
60:         values = [DEFAULT]
61:       end
62:       clone(:columns=>columns, :values=>values)._insert_sql
63:     end

Returns a literal representation of a value to be used as part of an SQL expression.

  DB[:items].literal("abc'def\\") #=> "'abc''def\\\\'"
  DB[:items].literal(:items__id) #=> "items.id"
  DB[:items].literal([1, 2, 3]) => "(1, 2, 3)"
  DB[:items].literal(DB[:items]) => "(SELECT * FROM items)"
  DB[:items].literal(:x + 1 > :y) => "((x + 1) > y)"

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 75
 75:     def literal_append(sql, v)
 76:       case v
 77:       when Symbol
 78:         literal_symbol_append(sql, v)
 79:       when String
 80:         case v
 81:         when LiteralString
 82:           sql << v
 83:         when SQL::Blob
 84:           literal_blob_append(sql, v)
 85:         else
 86:           literal_string_append(sql, v)
 87:         end
 88:       when Integer
 89:         sql << literal_integer(v)
 90:       when Hash
 91:         literal_hash_append(sql, v)
 92:       when SQL::Expression
 93:         literal_expression_append(sql, v)
 94:       when Float
 95:         sql << literal_float(v)
 96:       when BigDecimal
 97:         sql << literal_big_decimal(v)
 98:       when NilClass
 99:         sql << literal_nil
100:       when TrueClass
101:         sql << literal_true
102:       when FalseClass
103:         sql << literal_false
104:       when Array
105:         literal_array_append(sql, v)
106:       when Time
107:         sql << (v.is_a?(SQLTime) ? literal_sqltime(v) : literal_time(v))
108:       when DateTime
109:         sql << literal_datetime(v)
110:       when Date
111:         sql << literal_date(v)
112:       when Dataset
113:         literal_dataset_append(sql, v)
114:       else
115:         literal_other_append(sql, v)
116:       end
117:     end

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.

This method should be overridden by descendants if the support inserting multiple records in a single SQL statement.

[Source]

     # File lib/sequel/dataset/sql.rb, line 125
125:     def multi_insert_sql(columns, values)
126:       values.map{|r| insert_sql(columns, r)}
127:     end

Returns a SELECT SQL query string.

  dataset.select_sql # => "SELECT * FROM items"

[Source]

     # File lib/sequel/dataset/sql.rb, line 132
132:     def select_sql
133:       return static_sql(@opts[:sql]) if @opts[:sql]
134:       clause_sql(:select)
135:     end

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 138
138:     def sql
139:       select_sql
140:     end

Returns a TRUNCATE SQL query string. See truncate

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 145
145:     def truncate_sql
146:       if opts[:sql]
147:         static_sql(opts[:sql])
148:       else
149:         check_truncation_allowed!
150:         raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having]
151:         t = ''
152:         source_list_append(t, opts[:from])
153:         _truncate_sql(t)
154:       end
155:     end

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.

[Source]

     # File lib/sequel/dataset/sql.rb, line 164
164:     def update_sql(values = OPTS)
165:       return static_sql(opts[:sql]) if opts[:sql]
166:       check_modification_allowed!
167:       clone(:values=>values)._update_sql
168:     end

9 - Internal Methods relating to SQL Creation

These methods, while public, are not designed to be used directly by the end user.

Constants

EMULATED_FUNCTION_MAP = {}   Map of emulated function names to native function names.
WILDCARD = LiteralString.new('*').freeze
ALL = ' ALL'.freeze
AND_SEPARATOR = " AND ".freeze
APOS = "'".freeze
APOS_RE = /'/.freeze
ARRAY_EMPTY = '(NULL)'.freeze
AS = ' AS '.freeze
ASC = ' ASC'.freeze
BACKSLASH = "\\".freeze
BOOL_FALSE = "'f'".freeze
BOOL_TRUE = "'t'".freeze
BRACKET_CLOSE = ']'.freeze
BRACKET_OPEN = '['.freeze
CASE_ELSE = " ELSE ".freeze
CASE_END = " END)".freeze
CASE_OPEN = '(CASE'.freeze
CASE_THEN = " THEN ".freeze
CASE_WHEN = " WHEN ".freeze
CAST_OPEN = 'CAST('.freeze
COLON = ':'.freeze
COLUMN_REF_RE1 = Sequel::COLUMN_REF_RE1
COLUMN_REF_RE2 = Sequel::COLUMN_REF_RE2
COLUMN_REF_RE3 = Sequel::COLUMN_REF_RE3
COMMA = ', '.freeze
COMMA_SEPARATOR = COMMA
CONDITION_FALSE = '(1 = 0)'.freeze
CONDITION_TRUE = '(1 = 1)'.freeze
COUNT_FROM_SELF_OPTS = [:distinct, :group, :sql, :limit, :offset, :compounds]
COUNT_OF_ALL_AS_COUNT = SQL::Function.new(:count, WILDCARD).as(:count)
DATASET_ALIAS_BASE_NAME = 't'.freeze
DEFAULT = LiteralString.new('DEFAULT').freeze
DEFAULT_VALUES = " DEFAULT VALUES".freeze
DELETE = 'DELETE'.freeze
DELETE_CLAUSE_METHODS = clause_methods(:delete, %w'delete from where')
DESC = ' DESC'.freeze
DISTINCT = " DISTINCT".freeze
DOT = '.'.freeze
DOUBLE_APOS = "''".freeze
DOUBLE_QUOTE = '""'.freeze
EQUAL = ' = '.freeze
ESCAPE = " ESCAPE ".freeze
EXTRACT = 'extract('.freeze
EXISTS = ['EXISTS '.freeze].freeze
FOR_UPDATE = ' FOR UPDATE'.freeze
FORMAT_DATE = "'%Y-%m-%d'".freeze
FORMAT_DATE_STANDARD = "DATE '%Y-%m-%d'".freeze
FORMAT_OFFSET = "%+03i%02i".freeze
FORMAT_TIMESTAMP_RE = /%[Nz]/.freeze
FORMAT_TIMESTAMP_USEC = ".%06d".freeze
FORMAT_USEC = '%N'.freeze
FRAME_ALL = "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING".freeze
FRAME_ROWS = "ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW".freeze
FROM = ' FROM '.freeze
FUNCTION_EMPTY = '()'.freeze
GROUP_BY = " GROUP BY ".freeze
HAVING = " HAVING ".freeze
INSERT = "INSERT".freeze
INSERT_CLAUSE_METHODS = clause_methods(:insert, %w'insert into columns values')
INTO = " INTO ".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
LIMIT = " LIMIT ".freeze
N_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS
NOT_SPACE = 'NOT '.freeze
NULL = "NULL".freeze
NULLS_FIRST = " NULLS FIRST".freeze
NULLS_LAST = " NULLS LAST".freeze
OFFSET = " OFFSET ".freeze
ON = ' ON '.freeze
ON_PAREN = " ON (".freeze
ORDER_BY = " ORDER BY ".freeze
ORDER_BY_NS = "ORDER BY ".freeze
OVER = ' OVER '.freeze
PAREN_CLOSE = ')'.freeze
PAREN_OPEN = '('.freeze
PAREN_SPACE_OPEN = ' ('.freeze
PARTITION_BY = "PARTITION BY ".freeze
QUALIFY_KEYS = [:select, :where, :having, :order, :group]
QUESTION_MARK = '?'.freeze
QUESTION_MARK_RE = /\?/.freeze
QUOTE = '"'.freeze
QUOTE_RE = /"/.freeze
RETURNING = " RETURNING ".freeze
SELECT = 'SELECT'.freeze
SELECT_CLAUSE_METHODS = clause_methods(:select, %w'with select distinct columns from join where group having compounds order limit lock')
SET = ' SET '.freeze
SPACE = ' '.freeze
SQL_WITH = "WITH ".freeze
SPACE_WITH = " WITH ".freeze
TILDE = '~'.freeze
TIMESTAMP_FORMAT = "'%Y-%m-%d %H:%M:%S%N%z'".freeze
STANDARD_TIMESTAMP_FORMAT = "TIMESTAMP #{TIMESTAMP_FORMAT}".freeze
TWO_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS
REGEXP_OPERATORS = ::Sequel::SQL::ComplexExpression::REGEXP_OPERATORS
UNDERSCORE = '_'.freeze
UPDATE = 'UPDATE'.freeze
UPDATE_CLAUSE_METHODS = clause_methods(:update, %w'update table set where')
USING = ' USING ('.freeze
VALUES = " VALUES ".freeze
V190 = '1.9.0'.freeze
WHERE = " WHERE ".freeze

Public Class methods

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 177
177:     def self.clause_methods(type, clauses)
178:       clauses.map{|clause| "#{type}_#{clause}_sql""#{type}_#{clause}_sql"}.freeze
179:     end

Public Instance methods

SQL fragment for AliasedExpression

[Source]

     # File lib/sequel/dataset/sql.rb, line 299
299:     def aliased_expression_sql_append(sql, ae)
300:       literal_append(sql, ae.expression)
301:       as_sql_append(sql, ae.aliaz)
302:     end

SQL fragment for Array

[Source]

     # File lib/sequel/dataset/sql.rb, line 305
305:     def array_sql_append(sql, a)
306:       if a.empty?
307:         sql << ARRAY_EMPTY
308:       else
309:         sql << PAREN_OPEN
310:         expression_list_append(sql, a)
311:         sql << PAREN_CLOSE
312:       end
313:     end

SQL fragment for BooleanConstants

[Source]

     # File lib/sequel/dataset/sql.rb, line 316
316:     def boolean_constant_sql_append(sql, constant)
317:       if (constant == true || constant == false) && !supports_where_true?
318:         sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE)
319:       else
320:         literal_append(sql, constant)
321:       end
322:     end

SQL fragment for CaseExpression

[Source]

     # File lib/sequel/dataset/sql.rb, line 325
325:     def case_expression_sql_append(sql, ce)
326:       sql << CASE_OPEN
327:       if ce.expression?
328:         sql << SPACE
329:         literal_append(sql, ce.expression)
330:       end
331:       w = CASE_WHEN
332:       t = CASE_THEN
333:       ce.conditions.each do |c,r|
334:         sql << w
335:         literal_append(sql, c)
336:         sql << t
337:         literal_append(sql, r)
338:       end
339:       sql << CASE_ELSE
340:       literal_append(sql, ce.default)
341:       sql << CASE_END
342:     end

SQL fragment for the SQL CAST expression

[Source]

     # File lib/sequel/dataset/sql.rb, line 345
345:     def cast_sql_append(sql, expr, type)
346:       sql << CAST_OPEN
347:       literal_append(sql, expr)
348:       sql << AS << db.cast_type_literal(type).to_s
349:       sql << PAREN_CLOSE
350:     end

SQL fragment for specifying all columns in a given table

[Source]

     # File lib/sequel/dataset/sql.rb, line 353
353:     def column_all_sql_append(sql, ca)
354:       qualified_identifier_sql_append(sql, ca.table, WILDCARD)
355:     end

SQL fragment for the complex expression.

[Source]

     # File lib/sequel/dataset/sql.rb, line 358
358:     def complex_expression_sql_append(sql, op, args)
359:       case op
360:       when *IS_OPERATORS
361:         r = args.at(1)
362:         if r.nil? || supports_is_true?
363:           raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r]
364:           sql << PAREN_OPEN
365:           literal_append(sql, args.at(0))
366:           sql << SPACE << op.to_s << SPACE
367:           sql << val << PAREN_CLOSE
368:         elsif op == :IS
369:           complex_expression_sql_append(sql, "=""=", args)
370:         else
371:           complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new("!=""!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)])
372:         end
373:       when :IN, "NOT IN""NOT IN"
374:         cols = args.at(0)
375:         vals = args.at(1)
376:         col_array = true if cols.is_a?(Array)
377:         if vals.is_a?(Array)
378:           val_array = true
379:           empty_val_array = vals == []
380:         end
381:         if empty_val_array
382:           literal_append(sql, empty_array_value(op, cols))
383:         elsif col_array
384:           if !supports_multiple_column_in?
385:             if val_array
386:               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]})})
387:               literal_append(sql, op == :IN ? expr : ~expr)
388:             else
389:               old_vals = vals
390:               vals = vals.naked if vals.is_a?(Sequel::Dataset)
391:               vals = vals.to_a
392:               val_cols = old_vals.columns
393:               complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
394:             end
395:           else
396:             # If the columns and values are both arrays, use array_sql instead of
397:             # literal so that if values is an array of two element arrays, it
398:             # will be treated as a value list instead of a condition specifier.
399:             sql << PAREN_OPEN
400:             literal_append(sql, cols)
401:             sql << SPACE << op.to_s << SPACE
402:             if val_array
403:               array_sql_append(sql, vals)
404:             else
405:               literal_append(sql, vals)
406:             end
407:             sql << PAREN_CLOSE
408:           end
409:         else
410:           sql << PAREN_OPEN
411:           literal_append(sql, cols)
412:           sql << SPACE << op.to_s << SPACE
413:           literal_append(sql, vals)
414:           sql << PAREN_CLOSE
415:         end
416:       when :LIKE, 'NOT LIKE''NOT LIKE'
417:         sql << PAREN_OPEN
418:         literal_append(sql, args.at(0))
419:         sql << SPACE << op.to_s << SPACE
420:         literal_append(sql, args.at(1))
421:         sql << ESCAPE
422:         literal_append(sql, BACKSLASH)
423:         sql << PAREN_CLOSE
424:       when :ILIKE, 'NOT ILIKE''NOT ILIKE'
425:         complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : "NOT LIKE""NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)})
426:       when *TWO_ARITY_OPERATORS
427:         if REGEXP_OPERATORS.include?(op) && !supports_regexp?
428:           raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}"
429:         end
430:         sql << PAREN_OPEN
431:         literal_append(sql, args.at(0))
432:         sql << SPACE << op.to_s << SPACE
433:         literal_append(sql, args.at(1))
434:         sql << PAREN_CLOSE
435:       when *N_ARITY_OPERATORS
436:         sql << PAREN_OPEN
437:         c = false
438:         op_str = " #{op} "
439:         args.each do |a|
440:           sql << op_str if c
441:           literal_append(sql, a)
442:           c ||= true
443:         end
444:         sql << PAREN_CLOSE
445:       when :NOT
446:         sql << NOT_SPACE
447:         literal_append(sql, args.at(0))
448:       when :NOOP
449:         literal_append(sql, args.at(0))
450:       when 'B~''B~'
451:         sql << TILDE
452:         literal_append(sql, args.at(0))
453:       when :extract
454:         sql << EXTRACT << args.at(0).to_s << FROM
455:         literal_append(sql, args.at(1))
456:         sql << PAREN_CLOSE
457:       else
458:         raise(InvalidOperation, "invalid operator #{op}")
459:       end
460:     end

SQL fragment for constants

[Source]

     # File lib/sequel/dataset/sql.rb, line 463
463:     def constant_sql_append(sql, constant)
464:       sql << constant.to_s
465:     end

SQL fragment for delayed evaluations, evaluating the object and literalizing the returned value.

[Source]

     # File lib/sequel/dataset/sql.rb, line 469
469:     def delayed_evaluation_sql_append(sql, callable)
470:       literal_append(sql, callable.call)
471:     end

SQL fragment specifying an emulated SQL function call. By default, assumes just the function name may need to be emulated, adapters should set an EMULATED_FUNCTION_MAP hash mapping emulated functions to native functions in their dataset class to setup the emulation.

[Source]

     # File lib/sequel/dataset/sql.rb, line 478
478:     def emulated_function_sql_append(sql, f)
479:       _function_sql_append(sql, native_function_name(f.f), f.args)
480:     end

SQL fragment specifying an SQL function call without emulation.

[Source]

     # File lib/sequel/dataset/sql.rb, line 483
483:     def function_sql_append(sql, f)
484:       _function_sql_append(sql, f.f, f.args)
485:     end

SQL fragment specifying a JOIN clause without ON or USING.

[Source]

     # File lib/sequel/dataset/sql.rb, line 488
488:     def join_clause_sql_append(sql, jc)
489:       table = jc.table
490:       table_alias = jc.table_alias
491:       table_alias = nil if table == table_alias
492:       sql << SPACE << join_type_sql(jc.join_type) << SPACE
493:       identifier_append(sql, table)
494:       as_sql_append(sql, table_alias) if table_alias
495:     end

SQL fragment specifying a JOIN clause with ON.

[Source]

     # File lib/sequel/dataset/sql.rb, line 498
498:     def join_on_clause_sql_append(sql, jc)
499:       join_clause_sql_append(sql, jc)
500:       sql << ON
501:       literal_append(sql, filter_expr(jc.on))
502:     end

SQL fragment specifying a JOIN clause with USING.

[Source]

     # File lib/sequel/dataset/sql.rb, line 505
505:     def join_using_clause_sql_append(sql, jc)
506:       join_clause_sql_append(sql, jc)
507:       sql << USING
508:       column_list_append(sql, jc.using)
509:       sql << PAREN_CLOSE
510:     end

SQL fragment for NegativeBooleanConstants

[Source]

     # File lib/sequel/dataset/sql.rb, line 513
513:     def negative_boolean_constant_sql_append(sql, constant)
514:       sql << NOT_SPACE
515:       boolean_constant_sql_append(sql, constant)
516:     end

SQL fragment for the ordered expression, used in the ORDER BY clause.

[Source]

     # File lib/sequel/dataset/sql.rb, line 520
520:     def ordered_expression_sql_append(sql, oe)
521:       literal_append(sql, oe.expression)
522:       sql << (oe.descending ? DESC : ASC)
523:       case oe.nulls
524:       when :first
525:         sql << NULLS_FIRST
526:       when :last
527:         sql << NULLS_LAST
528:       end
529:     end

SQL fragment for a literal string with placeholders

[Source]

     # File lib/sequel/dataset/sql.rb, line 532
532:     def placeholder_literal_string_sql_append(sql, pls)
533:       args = pls.args
534:       str = pls.str
535:       sql << PAREN_OPEN if pls.parens
536:       if args.is_a?(Hash)
537:         re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
538:         loop do
539:           previous, q, str = str.partition(re)
540:           sql << previous
541:           literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
542:           break if str.empty?
543:         end
544:       elsif str.is_a?(Array)
545:         len = args.length
546:         str.each_with_index do |s, i|
547:           sql << s
548:           literal_append(sql, args[i]) unless i == len
549:         end
550:         unless str.length == args.length || str.length == args.length + 1
551:           raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
552:         end
553:       else
554:         i = -1
555:         match_len = args.length - 1
556:         loop do
557:           previous, q, str = str.partition(QUESTION_MARK)
558:           sql << previous
559:           literal_append(sql, args.at(i+=1)) unless q.empty?
560:           if str.empty?
561:             unless i == match_len
562:               raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder array"
563:             end
564:             break
565:           end
566:         end
567:       end
568:       sql << PAREN_CLOSE if pls.parens
569:     end

SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table). 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.

[Source]

     # File lib/sequel/dataset/sql.rb, line 575
575:     def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
576:       identifier_append(sql, table)
577:       sql << DOT
578:       identifier_append(sql, column)
579:     end

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.

[Source]

     # File lib/sequel/dataset/sql.rb, line 584
584:     def quote_identifier_append(sql, name)
585:       if name.is_a?(LiteralString)
586:         sql << name
587:       else
588:         name = name.value if name.is_a?(SQL::Identifier)
589:         name = input_identifier(name)
590:         if quote_identifiers?
591:           quoted_identifier_append(sql, name)
592:         else
593:           sql << name
594:         end
595:       end
596:     end

Separates the schema from the table and returns a string with them quoted (if quoting identifiers)

[Source]

     # File lib/sequel/dataset/sql.rb, line 600
600:     def quote_schema_table_append(sql, table)
601:       schema, table = schema_and_table(table)
602:       if schema
603:         quote_identifier_append(sql, schema)
604:         sql << DOT
605:       end
606:       quote_identifier_append(sql, table)
607:     end

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).

[Source]

     # File lib/sequel/dataset/sql.rb, line 612
612:     def quoted_identifier_append(sql, name)
613:       sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE
614:     end

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).

[Source]

     # File lib/sequel/dataset/sql.rb, line 623
623:     def schema_and_table(table_name, sch=nil)
624:       sch = sch.to_s if sch
625:       case table_name
626:       when Symbol
627:         s, t, _ = split_symbol(table_name)
628:         [s||sch, t]
629:       when SQL::QualifiedIdentifier
630:         [table_name.table.to_s, table_name.column.to_s]
631:       when SQL::Identifier
632:         [sch, table_name.value.to_s]
633:       when String
634:         [sch, table_name]
635:       else
636:         raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
637:       end
638:     end

Splits table_name into an array of strings.

  ds.split_qualifiers(:s) # ['s']
  ds.split_qualifiers(:t__s) # ['t', 's']
  ds.split_qualifiers(Sequel.qualify(:d, :t__s)) # ['d', 't', 's']
  ds.split_qualifiers(Sequel.qualify(:h__d, :t__s)) # ['h', 'd', 't', 's']

[Source]

     # File lib/sequel/dataset/sql.rb, line 646
646:     def split_qualifiers(table_name, *args)
647:       case table_name
648:       when SQL::QualifiedIdentifier
649:         split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
650:       else
651:         sch, table = schema_and_table(table_name, *args)
652:         sch ? [sch, table] : [table]
653:       end
654:     end

SQL fragment for specifying subscripts (SQL array accesses)

[Source]

     # File lib/sequel/dataset/sql.rb, line 657
657:     def subscript_sql_append(sql, s)
658:       literal_append(sql, s.f)
659:       sql << BRACKET_OPEN
660:       if s.sub.length == 1 && (range = s.sub.first).is_a?(Range)
661:         literal_append(sql, range.begin)
662:         sql << COLON
663:         e = range.end
664:         e -= 1 if range.exclude_end? && e.is_a?(Integer)
665:         literal_append(sql, e)
666:       else
667:         expression_list_append(sql, s.sub)
668:       end
669:       sql << BRACKET_CLOSE
670:     end

The SQL fragment for the given window function‘s function and window.

[Source]

     # File lib/sequel/dataset/sql.rb, line 714
714:     def window_function_sql_append(sql, function, window)
715:       literal_append(sql, function)
716:       sql << OVER
717:       literal_append(sql, window)
718:     end

The SQL fragment for the given window‘s options.

[Source]

     # File lib/sequel/dataset/sql.rb, line 673
673:     def window_sql_append(sql, opts)
674:       raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
675:       sql << PAREN_OPEN
676:       window, part, order, frame = opts.values_at(:window, :partition, :order, :frame)
677:       space = false
678:       space_s = SPACE
679:       if window
680:         literal_append(sql, window)
681:         space = true
682:       end
683:       if part
684:         sql << space_s if space
685:         sql << PARTITION_BY
686:         expression_list_append(sql, Array(part))
687:         space = true
688:       end
689:       if order
690:         sql << space_s if space
691:         sql << ORDER_BY_NS
692:         expression_list_append(sql, Array(order))
693:         space = true
694:       end
695:       case frame
696:         when nil
697:           # nothing
698:         when :all
699:           sql << space_s if space
700:           sql << FRAME_ALL
701:         when :rows
702:           sql << space_s if space
703:           sql << FRAME_ROWS
704:         when String
705:           sql << space_s if space
706:           sql << frame
707:         else
708:           raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil"
709:       end
710:       sql << PAREN_CLOSE
711:     end

Protected Instance methods

Formats in INSERT statement using the stored columns and values.

[Source]

     # File lib/sequel/dataset/sql.rb, line 723
723:     def _insert_sql
724:       clause_sql(:insert)
725:     end

Formats an UPDATE statement using the stored values.

[Source]

     # File lib/sequel/dataset/sql.rb, line 728
728:     def _update_sql
729:       clause_sql(:update)
730:     end

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 734
734:     def compound_from_self
735:       (@opts[:limit] || @opts[:order]) ? from_self : self
736:     end

1 - Methods that return modified datasets

These methods all return modified copies of the receiver.

Constants

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).
COLUMN_CHANGE_OPTS = [:select, :sql, :from, :join].freeze   The dataset options that require the removal of cached columns if changed.
NON_SQL_OPTIONS = [:server, :defaults, :overrides, :graph, :eager_graph, :graph_aliases]   Which options don‘t affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table.
CONDITIONED_JOIN_TYPES = [:inner, :full_outer, :right_outer, :left_outer, :full, :right, :left]   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.
UNCONDITIONED_JOIN_TYPES = [:natural, :natural_left, :natural_right, :natural_full, :cross]   These symbols have _join methods created (e.g. natural_join) that call join_table with the symbol. They only accept a single table argument which is passed to join_table, and they raise an error if called with a block.
JOIN_METHODS = (CONDITIONED_JOIN_TYPES + UNCONDITIONED_JOIN_TYPES).map{|x| "#{x}_join".to_sym} + [:join, :join_table]   All methods that return modified datasets with a joined table added.
QUERY_METHODS = (<<-METHS).split.map{|x| x.to_sym} + JOIN_METHODS add_graph_aliases and distinct except exclude exclude_having exclude_where filter for_update from from_self graph grep group group_and_count group_by having intersect invert limit lock_style naked or order order_append order_by order_more order_prepend paginate qualify query reverse reverse_order select select_all select_append select_group select_more server set_defaults set_graph_aliases set_overrides unfiltered ungraphed ungrouped union unlimited unordered where with with_recursive with_sql METHS ).split.map{|x| x.to_sym} + JOIN_METHODS   Methods that return modified datasets

Public Class methods

Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should either be a Module that the dataset is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.

If mod is a module, this also registers a Database extension that will extend all of the database‘s datasets.

[Source]

    # File lib/sequel/dataset/query.rb, line 55
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:         else
62:           block = mod
63:         end
64:       end
65:       Sequel.synchronize{EXTENSIONS[ext] = block}
66:     end

Public Instance methods

Alias for where.

[Source]

    # File lib/sequel/dataset/query.rb, line 69
69:     def and(*cond, &block)
70:       where(*cond, &block)
71:     end

Returns a new clone of the dataset with 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.

[Source]

    # File lib/sequel/dataset/query.rb, line 77
77:     def clone(opts = nil)
78:       c = super()
79:       if opts
80:         c.instance_variable_set(:@opts, @opts.merge(opts))
81:         c.instance_variable_set(:@columns, nil) if @columns && !opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)}
82:       else
83:         c.instance_variable_set(:@opts, @opts.dup)
84:       end
85:       c
86:     end

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. 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

[Source]

     # File lib/sequel/dataset/query.rb, line 97
 97:     def distinct(*args)
 98:       raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on?
 99:       clone(:distinct => args)
100:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 119
119:     def except(dataset, opts=OPTS)
120:       raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
121:       raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
122:       compound_clone(:except, dataset, opts)
123:     end

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))

[Source]

     # File lib/sequel/dataset/query.rb, line 133
133:     def exclude(*cond, &block)
134:       _filter_or_exclude(true, :where, *cond, &block)
135:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 141
141:     def exclude_having(*cond, &block)
142:       _filter_or_exclude(true, :having, *cond, &block)
143:     end

Alias for exclude.

[Source]

     # File lib/sequel/dataset/query.rb, line 146
146:     def exclude_where(*cond, &block)
147:       exclude(*cond, &block)
148:     end

Return a clone of the dataset loaded with the extensions, see extension!.

[Source]

     # File lib/sequel/dataset/query.rb, line 151
151:     def extension(*exts)
152:       clone.extension!(*exts)
153:     end

Alias for where.

[Source]

     # File lib/sequel/dataset/query.rb, line 156
156:     def filter(*cond, &block)
157:       where(*cond, &block)
158:     end

Returns a cloned dataset with a :update lock style.

  DB[:table].for_update # SELECT * FROM table FOR UPDATE

[Source]

     # File lib/sequel/dataset/query.rb, line 163
163:     def for_update
164:       lock_style(:update)
165:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 176
176:     def from(*source, &block)
177:       virtual_row_columns(source, block)
178:       table_alias_num = 0
179:       ctes = nil
180:       source.map! do |s|
181:         case s
182:         when Dataset
183:           if hoist_cte?(s)
184:             ctes ||= []
185:             ctes += s.opts[:with]
186:             s = s.clone(:with=>nil)
187:           end
188:           SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
189:         when Symbol
190:           sch, table, aliaz = split_symbol(s)
191:           if aliaz
192:             s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table)
193:             SQL::AliasedExpression.new(s, aliaz.to_sym)
194:           else
195:             s
196:           end
197:         else
198:           s
199:         end
200:       end
201:       o = {:from=>source.empty? ? nil : source}
202:       o[:with] = (opts[:with] || []) + ctes if ctes
203:       o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
204:       clone(o)
205:     end

Returns a dataset selecting from the current dataset. Supplying the :alias option controls the alias of the result.

  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

[Source]

     # File lib/sequel/dataset/query.rb, line 218
218:     def from_self(opts=OPTS)
219:       fs = {}
220:       @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)}
221:       clone(fs).from(opts[:alias] ? as(opts[:alias]) : self)
222:     end

Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions (which are only supported on MySQL and PostgreSQL). 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%')

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

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

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

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

[Source]

     # File lib/sequel/dataset/query.rb, line 255
255:     def grep(columns, patterns, opts=OPTS)
256:       if opts[:all_patterns]
257:         conds = Array(patterns).map do |pat|
258:           SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
259:         end
260:         where(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds))
261:       else
262:         conds = Array(columns).map do |c|
263:           SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
264:         end
265:         where(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds))
266:       end
267:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 276
276:     def group(*columns, &block)
277:       virtual_row_columns(columns, block)
278:       clone(:group => (columns.compact.empty? ? nil : columns))
279:     end

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(:first_name___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}, ...]

[Source]

     # File lib/sequel/dataset/query.rb, line 307
307:     def group_and_count(*columns, &block)
308:       select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT)
309:     end

Alias of group

[Source]

     # File lib/sequel/dataset/query.rb, line 282
282:     def group_by(*columns, &block)
283:       group(*columns, &block)
284:     end

Adds the appropriate CUBE syntax to GROUP BY.

[Source]

     # File lib/sequel/dataset/query.rb, line 312
312:     def group_cube
313:       raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
314:       clone(:group_options=>:cube)
315:     end

Adds the appropriate ROLLUP syntax to GROUP BY.

[Source]

     # File lib/sequel/dataset/query.rb, line 318
318:     def group_rollup
319:       raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
320:       clone(:group_options=>:rollup)
321:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 327
327:     def having(*cond, &block)
328:       _filter(:having, *cond, &block)
329:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 348
348:     def intersect(dataset, opts=OPTS)
349:       raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
350:       raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
351:       compound_clone(:intersect, dataset, opts)
352:     end

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))

[Source]

     # File lib/sequel/dataset/query.rb, line 362
362:     def invert
363:       having, where = @opts.values_at(:having, :where)
364:       if having.nil? && where.nil?
365:         where(false)
366:       else
367:         o = {}
368:         o[:having] = SQL::BooleanExpression.invert(having) if having
369:         o[:where] = SQL::BooleanExpression.invert(where) if where
370:         clone(o)
371:       end
372:     end

Alias of inner_join

[Source]

     # File lib/sequel/dataset/query.rb, line 375
375:     def join(*args, &block)
376:       inner_join(*args, &block)
377:     end

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 - Depends on type:
  • expr - specifies conditions, depends on type:
    • Hash, Array of two element arrays - 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.
    • Everything else - pretty much the same as a using the argument in a call to where, 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 any of the following keys:
    • :table_alias - the name of the table‘s alias when joining, necessary for joining to the same table more than once. No alias is used by default.
    • :implicit_qualifier - The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.
    • :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, :b___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)))

[Source]

     # File lib/sequel/dataset/query.rb, line 433
433:     def join_table(type, table, expr=nil, options=OPTS, &block)
434:       if hoist_cte?(table)
435:         s, ds = hoist_cte(table)
436:         return s.join_table(type, ds, expr, options, &block)
437:       end
438: 
439:       using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
440:       if using_join && !supports_join_using?
441:         h = {}
442:         expr.each{|e| h[e] = e}
443:         return join_table(type, table, h, options)
444:       end
445: 
446:       table_alias = options[:table_alias]
447:       last_alias = options[:implicit_qualifier]
448:       qualify_type = options[:qualify]
449: 
450:       if table.is_a?(Dataset)
451:         if table_alias.nil?
452:           table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
453:           table_alias = dataset_alias(table_alias_num)
454:         end
455:         table_name = table_alias
456:       else
457:         table, implicit_table_alias = split_alias(table)
458:         table_alias ||= implicit_table_alias
459:         table_name = table_alias || table
460:       end
461: 
462:       join = if expr.nil? and !block
463:         SQL::JoinClause.new(type, table, table_alias)
464:       elsif using_join
465:         raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
466:         SQL::JoinUsingClause.new(expr, type, table, table_alias)
467:       else
468:         last_alias ||= @opts[:last_joined_table] || first_source_alias
469:         if Sequel.condition_specifier?(expr)
470:           expr = expr.collect do |k, v|
471:             qualify_type = default_join_table_qualification if qualify_type.nil?
472:             case qualify_type
473:             when false
474:               nil # Do no qualification
475:             when :deep
476:               k = Sequel::Qualifier.new(self, table_name).transform(k)
477:               v = Sequel::Qualifier.new(self, last_alias).transform(v)
478:             else
479:               k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
480:               v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
481:             end
482:             [k,v]
483:           end
484:           expr = SQL::BooleanExpression.from_value_pairs(expr)
485:         end
486:         if block
487:           expr2 = yield(table_name, last_alias, @opts[:join] || [])
488:           expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
489:         end
490:         SQL::JoinOnClause.new(expr, type, table, table_alias)
491:       end
492: 
493:       opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name}
494:       opts[:num_dataset_sources] = table_alias_num if table_alias_num
495:       clone(opts)
496:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 515
515:     def limit(l, o = (no_offset = true; nil))
516:       return from_self.limit(l, o) if @opts[:sql]
517: 
518:       if l.is_a?(Range)
519:         o = l.first
520:         l = l.last - l.first + (l.exclude_end? ? 0 : 1)
521:       end
522:       l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
523:       if l.is_a?(Integer)
524:         raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
525:       end
526:       opts = {:limit => l}
527:       if o
528:         o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
529:         if o.is_a?(Integer)
530:           raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
531:         end
532:         opts[:offset] = o
533:       elsif !no_offset
534:         opts[:offset] = nil
535:       end
536:       clone(opts)
537:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 548
548:     def lock_style(style)
549:       clone(:lock => style)
550:     end

Returns a cloned dataset without a row_proc.

  ds = DB[:items]
  ds.row_proc = proc{|r| r.invert}
  ds.all # => [{2=>:id}]
  ds.naked.all # => [{:id=>2}]

[Source]

     # File lib/sequel/dataset/query.rb, line 558
558:     def naked
559:       ds = clone
560:       ds.row_proc = nil
561:       ds
562:     end

Adds an alternate filter to an existing filter using OR. If no filter exists an Error is raised.

  DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b

[Source]

     # File lib/sequel/dataset/query.rb, line 568
568:     def or(*cond, &block)
569:       cond = cond.first if cond.size == 1
570:       v = @opts[:where]
571:       if v.nil? || (cond.respond_to?(:empty?) && cond.empty? && !block)
572:         clone
573:       else
574:         clone(:where => SQL::BooleanExpression.new(:OR, v, filter_expr(cond, &block)))
575:       end
576:     end

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(: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

[Source]

     # File lib/sequel/dataset/query.rb, line 592
592:     def order(*columns, &block)
593:       virtual_row_columns(columns, block)
594:       clone(:order => (columns.compact.empty?) ? nil : columns)
595:     end

Alias of order_more, for naming consistency with order_prepend.

[Source]

     # File lib/sequel/dataset/query.rb, line 598
598:     def order_append(*columns, &block)
599:       order_more(*columns, &block)
600:     end

Alias of order

[Source]

     # File lib/sequel/dataset/query.rb, line 603
603:     def order_by(*columns, &block)
604:       order(*columns, &block)
605:     end

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_more(:b) # SELECT * FROM items ORDER BY a, b

[Source]

     # File lib/sequel/dataset/query.rb, line 612
612:     def order_more(*columns, &block)
613:       columns = @opts[:order] + columns if @opts[:order]
614:       order(*columns, &block)
615:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 622
622:     def order_prepend(*columns, &block)
623:       ds = order(*columns, &block)
624:       @opts[:order] ? ds.order_more(*@opts[:order]) : ds
625:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 634
634:     def qualify(table=first_source)
635:       o = @opts
636:       return clone if o[:sql]
637:       h = {}
638:       (o.keys & QUALIFY_KEYS).each do |k|
639:         h[k] = qualified_expression(o[k], table)
640:       end
641:       h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty?
642:       clone(h)
643:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 653
653:     def returning(*values)
654:       clone(:returning=>values)
655:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 664
664:     def reverse(*order, &block)
665:       virtual_row_columns(order, block)
666:       order(*invert_order(order.empty? ? @opts[:order] : order))
667:     end

Alias of reverse

[Source]

     # File lib/sequel/dataset/query.rb, line 670
670:     def reverse_order(*order, &block)
671:       reverse(*order, &block)
672:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 681
681:     def select(*columns, &block)
682:       virtual_row_columns(columns, block)
683:       clone(:select => columns)
684:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 693
693:     def select_all(*tables)
694:       if tables.empty?
695:         clone(:select => nil)
696:       else
697:         select(*tables.map{|t| i, a = split_alias(t); a || i}.map{|t| SQL::ColumnAll.new(t)})
698:       end
699:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 708
708:     def select_append(*columns, &block)
709:       cur_sel = @opts[:select]
710:       if !cur_sel || cur_sel.empty?
711:         unless supports_select_all_and_column?
712:           return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_more(*columns, &block)
713:         end
714:         cur_sel = [WILDCARD]
715:       end
716:       select(*(cur_sel + columns), &block)
717:     end

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(:c___a){f(c2)}
  # SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)

[Source]

     # File lib/sequel/dataset/query.rb, line 728
728:     def select_group(*columns, &block)
729:       virtual_row_columns(columns, block)
730:       select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
731:     end

Alias for select_append.

[Source]

     # File lib/sequel/dataset/query.rb, line 734
734:     def select_more(*columns, &block)
735:       select_append(*columns, &block)
736:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 747
747:     def server(servr)
748:       clone(:server=>servr)
749:     end

Unbind bound variables from this dataset‘s filter and return an array of two objects. The first object is a modified dataset where the filter has been replaced with one that uses bound variable placeholders. The second object is the hash of unbound variables. You can then prepare and execute (or just call) the dataset with the bound variables to get results.

  ds, bv = DB[:items].where(:a=>1).unbind
  ds # SELECT * FROM items WHERE (a = $a)
  bv #  {:a => 1}
  ds.call(:select, bv)

[Source]

     # File lib/sequel/dataset/query.rb, line 761
761:     def unbind
762:       u = Unbinder.new
763:       ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join]))
764:       [ds, u.binds]
765:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 771
771:     def unfiltered
772:       clone(:where => nil, :having => nil)
773:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 779
779:     def ungrouped
780:       clone(:group => nil, :having => nil)
781:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 799
799:     def union(dataset, opts=OPTS)
800:       compound_clone(:union, dataset, opts)
801:     end

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

  DB[:items].limit(10, 20).unlimited # SELECT * FROM items

[Source]

     # File lib/sequel/dataset/query.rb, line 806
806:     def unlimited
807:       clone(:limit=>nil, :offset=>nil)
808:     end

Returns a copy of the dataset with no order.

  DB[:items].order(:a).unordered # SELECT * FROM items

[Source]

     # File lib/sequel/dataset/query.rb, line 813
813:     def unordered
814:       order(nil)
815:     end

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

Accepts the following argument types:

  • Hash - list of equality/inclusion expressions
  • Array - depends:
    • If first member is a string, assumes the rest of the arguments are parameters and interpolates them into the string.
    • If all members are arrays of length two, treats the same way as a hash, except it allows for duplicate keys to be specified.
    • Otherwise, treats each argument as a separate condition.
  • String - taken literally
  • Symbol - taken as a boolean column argument (e.g. WHERE active)
  • Sequel::SQL::BooleanExpression - 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('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('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 the "Dataset Filtering" guide for more examples and details.

[Source]

     # File lib/sequel/dataset/query.rb, line 867
867:     def where(*cond, &block)
868:       _filter(:where, *cond, &block)
869:     end

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
  DB[:items].with(:items, DB[:syx].where(:name.like('A%')))
  # WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%')) SELECT * FROM items

[Source]

     # File lib/sequel/dataset/query.rb, line 879
879:     def with(name, dataset, opts=OPTS)
880:       raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
881:       if hoist_cte?(dataset)
882:         s, ds = hoist_cte(dataset)
883:         s.with(name, ds, opts)
884:       else
885:         clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)])
886:       end
887:     end

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.
  DB[:t].with_recursive(:t,
    DB[:i1].select(:id, :parent_id).where(:parent_id=>nil),
    DB[:i1].join(:t, :id=>:parent_id).select(:i1__id, :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"

[Source]

     # File lib/sequel/dataset/query.rb, line 905
905:     def with_recursive(name, nonrecursive, recursive, opts=OPTS)
906:       raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
907:       if hoist_cte?(nonrecursive)
908:         s, ds = hoist_cte(nonrecursive)
909:         s.with_recursive(name, ds, recursive, opts)
910:       elsif hoist_cte?(recursive)
911:         s, ds = hoist_cte(recursive)
912:         s.with_recursive(name, nonrecursive, ds, opts)
913:       else
914:         clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))])
915:       end
916:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 930
930:     def with_sql(sql, *args)
931:       if sql.is_a?(Symbol)
932:         sql = send(sql, *args)
933:       else
934:         sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
935:       end
936:       clone(:sql=>sql)
937:     end

Protected Instance methods

Add the dataset to the list of compounds

[Source]

     # File lib/sequel/dataset/query.rb, line 942
942:     def compound_clone(type, dataset, opts)
943:       if hoist_cte?(dataset)
944:         s, ds = hoist_cte(dataset)
945:         return s.compound_clone(type, ds, opts)
946:       end
947:       ds = compound_from_self.clone(:compounds=>Array(@opts[:compounds]).map{|x| x.dup} + [[type, dataset.compound_from_self, opts[:all]]])
948:       opts[:from_self] == false ? ds : ds.from_self(opts)
949:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 952
952:     def options_overlap(opts)
953:       !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty?
954:     end

Whether this dataset is a simple SELECT * FROM table.

[Source]

     # File lib/sequel/dataset/query.rb, line 957
957:     def simple_select_all?
958:       o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)}
959:       o.length == 1 && (f = o[:from]) && f.length == 1 && (f.first.is_a?(Symbol) || f.first.is_a?(SQL::AliasedExpression))
960:     end

2 - Methods that execute code on the database

These methods all execute the dataset‘s SQL on the database. They don‘t return modified datasets, so if used in a method chain they should be the last method called.

Constants

ACTION_METHODS = (<<-METHS).split.map{|x| x.to_sym} << [] []= all avg count columns columns! delete each empty? fetch_rows first first! get import insert insert_multiple interval last map max min multi_insert paged_each range select_hash select_hash_groups select_map select_order_map set single_record single_value sum to_csv to_hash to_hash_groups truncate update METHS ).split.map{|x| x.to_sym}   Action methods defined by Sequel that execute code on the database.
DatasetClass = self
DatasetClass = self
JAVA_SQL_TIMESTAMP = Java::JavaSQL::Timestamp   Cache Java class constants to speed up lookups
JAVA_SQL_TIME = Java::JavaSQL::Time
JAVA_SQL_DATE = Java::JavaSQL::Date
JAVA_SQL_BLOB = Java::JavaSQL::Blob
JAVA_SQL_CLOB = Java::JavaSQL::Clob
JAVA_BUFFERED_READER = Java::JavaIo::BufferedReader
JAVA_BIG_DECIMAL = Java::JavaMath::BigDecimal
JAVA_BYTE_ARRAY = Java::byte[]
JAVA_UUID = Java::JavaUtil::UUID
JAVA_HASH_MAP = Java::JavaUtil::HashMap
TYPE_TRANSLATOR_INSTANCE = tt = TYPE_TRANSLATOR.new
DECIMAL_METHOD = tt.method(:decimal)   Cache type translator methods so that duplicate Method objects are not created.
TIME_METHOD = tt.method(:time)
DATE_METHOD = tt.method(:date)
BUFFERED_READER_METHOD = tt.method(:buffered_reader)
BYTE_ARRAY_METHOD = tt.method(:byte_array)
BLOB_METHOD = tt.method(:blob)
CLOB_METHOD = tt.method(:clob)
UUID_METHOD = tt.method(:uuid)
HASH_MAP_METHOD = tt.method(:hash_map)
DatasetClass = self
DatasetClass = self
DatasetClass = self
PREPARED_ARG_PLACEHOLDER = ':'.freeze
OPTS = Sequel::OPTS

Attributes

convert_types  [RW]  Whether to convert some Java types to ruby types when retrieving rows. Uses the database‘s setting by default, can be set to false to roughly double performance when fetching rows.

Public Instance methods

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)

[Source]

    # File lib/sequel/dataset/actions.rb, line 24
24:     def <<(arg)
25:       insert(arg)
26:       self
27:     end

Returns the first record matching the conditions. Examples:

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

[Source]

    # File lib/sequel/dataset/actions.rb, line 33
33:     def [](*conditions)
34:       raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
35:       first(*conditions)
36:     end

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}

[Source]

    # File lib/sequel/dataset/actions.rb, line 46
46:     def all(&block)
47:       a = []
48:       each{|r| a << r}
49:       post_load(a)
50:       a.each(&block) if block
51:       a
52:     end

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

[Source]

    # File lib/sequel/dataset/actions.rb, line 61
61:     def avg(column=Sequel.virtual_row(&Proc.new))
62:       aggregate_dataset.get{avg(column).as(:avg)}
63:     end

Execute the given type of statement with the hash of values.

[Source]

     # File lib/sequel/adapters/sqlite.rb, line 348
348:       def call(type, bind_vars={}, *values, &block)
349:         ps = to_prepared_statement(type, values)
350:         ps.extend(BindArgumentMethods)
351:         ps.call(bind_vars, &block)
352:       end

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]

[Source]

    # File lib/sequel/dataset/actions.rb, line 74
74:     def columns
75:       return @columns if @columns
76:       ds = unfiltered.unordered.naked.clone(:distinct => nil, :limit => 1, :offset=>nil)
77:       ds.each{break}
78:       @columns = ds.instance_variable_get(:@columns)
79:       @columns || []
80:     end

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

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

[Source]

    # File lib/sequel/dataset/actions.rb, line 87
87:     def columns!
88:       @columns = nil
89:       columns
90:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 103
103:     def count(arg=(no_arg=true), &block)
104:       if no_arg
105:         if block
106:           arg = Sequel.virtual_row(&block)
107:           aggregate_dataset.get{count(arg).as(count)}
108:         else
109:           aggregate_dataset.get{count(:*){}.as(count)}.to_i
110:         end
111:       elsif block
112:         raise Error, 'cannot provide both argument and block to Dataset#count'
113:       else
114:         aggregate_dataset.get{count(arg).as(count)}
115:       end
116:     end

Deletes the records in the dataset. The returned value should be number of records deleted, but that is adapter dependent.

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 123
123:     def delete(&block)
124:       sql = delete_sql
125:       if uses_returning?(:delete)
126:         returning_fetch_rows(sql, &block)
127:       else
128:         execute_dui(sql)
129:       end
130:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 141
141:     def each
142:       if row_proc = @row_proc
143:         fetch_rows(select_sql){|r| yield row_proc.call(r)}
144:       else
145:         fetch_rows(select_sql){|r| yield r}
146:       end
147:       self
148:     end

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

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 154
154:     def empty?
155:       get(Sequel::SQL::AliasedExpression.new(1, :one)).nil?
156:     end

Yield a hash for each row in the dataset.

[Source]

     # File lib/sequel/adapters/sqlite.rb, line 355
355:       def fetch_rows(sql)
356:         execute(sql) do |result|
357:           i = -1
358:           cps = db.conversion_procs
359:           type_procs = result.types.map{|t| cps[base_type_name(t)]}
360:           cols = result.columns.map{|c| i+=1; [output_identifier(c), i, type_procs[i]]}
361:           @columns = cols.map{|c| c.first}
362:           result.each do |values|
363:             row = {}
364:             cols.each do |name,id,type_proc|
365:               v = values[id]
366:               if type_proc && v
367:                 v = type_proc.call(v)
368:               end
369:               row[name] = v
370:             end
371:             yield row
372:           end
373:         end
374:       end

Execute the SQL on the database and yield the rows as hashes with symbol keys.

[Source]

     # File lib/sequel/adapters/do.rb, line 155
155:       def fetch_rows(sql)
156:         execute(sql) do |reader|
157:           cols = @columns = reader.fields.map{|f| output_identifier(f)}
158:           while(reader.next!) do
159:             h = {}
160:             cols.zip(reader.values).each{|k, v| h[k] = v}
161:             yield h
162:           end
163:         end
164:         self
165:       end

Correctly return rows from the database and return them as hashes.

[Source]

     # File lib/sequel/adapters/jdbc.rb, line 670
670:       def fetch_rows(sql, &block)
671:         execute(sql){|result| process_result_set(result, &block)}
672:         self
673:       end

Yield all rows matching this dataset. If the dataset is set to split multiple statements, yield arrays of hashes one per statement instead of yielding results for all statements as hashes.

[Source]

     # File lib/sequel/adapters/mysql.rb, line 295
295:       def fetch_rows(sql)
296:         execute(sql) do |r|
297:           i = -1
298:           cps = db.conversion_procs
299:           cols = r.fetch_fields.map do |f| 
300:             # Pretend tinyint is another integer type if its length is not 1, to
301:             # avoid casting to boolean if Sequel::MySQL.convert_tinyint_to_bool
302:             # is set.
303:             type_proc = f.type == 1 && cast_tinyint_integer?(f) ? cps[2] : cps[f.type]
304:             [output_identifier(f.name), type_proc, i+=1]
305:           end
306:           @columns = cols.map{|c| c.first}
307:           if opts[:split_multiple_result_sets]
308:             s = []
309:             yield_rows(r, cols){|h| s << h}
310:             yield s
311:           else
312:             yield_rows(r, cols){|h| yield h}
313:           end
314:         end
315:         self
316:       end

Set the columns and yield the hashes to the block.

[Source]

     # File lib/sequel/adapters/swift.rb, line 132
132:       def fetch_rows(sql)
133:         execute(sql) do |res|
134:           col_map = {}
135:           @columns = res.fields.map do |c|
136:             col_map[c] = output_identifier(c)
137:           end
138:           res.each do |r|
139:             h = {}
140:             r.each do |k, v|
141:               h[col_map[k]] = v.is_a?(StringIO) ? SQL::Blob.new(v.read) : v
142:             end
143:             yield h
144:           end
145:         end
146:         self
147:       end

If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If no argument is passed, it returns the first matching record. If any other type of argument(s) is passed, it is given to 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("id = 3") # SELECT * FROM table WHERE (id = 3) LIMIT 1
  # => {:id=>3}

  DB[:table].first("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("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}]

[Source]

     # File lib/sequel/dataset/actions.rb, line 193
193:     def first(*args, &block)
194:       ds = block ? filter(&block) : self
195: 
196:       if args.empty?
197:         ds.single_record
198:       else
199:         args = (args.size == 1) ? args.first : args
200:         if args.is_a?(Integer)
201:           ds.limit(args).all
202:         else
203:           ds.filter(args).single_record
204:         end
205:       end
206:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 210
210:     def first!(*args, &block)
211:       first(*args, &block) || raise(Sequel::NoMatchingRow)
212:     end

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']

[Source]

     # File lib/sequel/dataset/actions.rb, line 232
232:     def get(column=(no_arg=true; nil), &block)
233:       ds = naked
234:       if block
235:         raise(Error, ARG_BLOCK_ERROR_MSG) unless no_arg
236:         ds = ds.select(&block)
237:         column = ds.opts[:select]
238:         column = nil if column.is_a?(Array) && column.length < 2
239:       else
240:         ds = if column.is_a?(Array)
241:           ds.select(*column)
242:         else
243:           ds.select(auto_alias_expression(column))
244:         end
245:       end
246: 
247:       if column.is_a?(Array)
248:        if r = ds.single_record
249:          r.values_at(*hash_key_symbols(column))
250:        end
251:       else
252:         ds.single_value
253:       end
254:     end

Don‘t allow graphing a dataset that splits multiple statements

[Source]

     # File lib/sequel/adapters/mysql.rb, line 319
319:       def graph(*)
320:         raise(Error, "Can't graph a dataset that splits multiple result sets") if opts[:split_multiple_result_sets]
321:         super
322:       end

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.

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)

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.
:server :Set the server/shard to use for the transaction and insert queries.
:slice :Same as :commit_every, :commit_every takes precedence.

[Source]

     # File lib/sequel/dataset/actions.rb, line 279
279:     def import(columns, values, opts=OPTS)
280:       return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)
281: 
282:       return if values.empty?
283:       raise(Error, IMPORT_ERROR_MSG) if columns.empty?
284:       ds = opts[:server] ? server(opts[:server]) : self
285:       
286:       if slice_size = opts[:commit_every] || opts[:slice]
287:         offset = 0
288:         rows = []
289:         while offset < values.length
290:           rows << ds._import(columns, values[offset, slice_size], opts)
291:           offset += slice_size
292:         end
293:         rows.flatten
294:       else
295:         ds._import(columns, values, opts)
296:       end
297:     end

Inserts values into the associated table. The returned value is generally the value of the primary key for the inserted row, but that is adapter dependent.

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 an 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

[Source]

     # File lib/sequel/dataset/actions.rb, line 334
334:     def insert(*values, &block)
335:       sql = insert_sql(*values)
336:       if uses_returning?(:insert)
337:         returning_fetch_rows(sql, &block)
338:       else
339:         execute_insert(sql)
340:       end
341:     end

Returns the interval between minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.

  DB[:table].interval(:id) # SELECT (max(id) - min(id)) FROM table LIMIT 1
  # => 6
  DB[:table].interval{function(column)} # SELECT (max(function(column)) - min(function(column))) FROM table LIMIT 1
  # => 7

[Source]

     # File lib/sequel/dataset/actions.rb, line 350
350:     def interval(column=Sequel.virtual_row(&Proc.new))
351:       aggregate_dataset.get{(max(column) - min(column)).as(:interval)}
352:     end

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}]

[Source]

     # File lib/sequel/dataset/actions.rb, line 364
364:     def last(*args, &block)
365:       raise(Error, 'No order specified') unless @opts[:order]
366:       reverse.first(*args, &block)
367:     end

Maps column values for each record in the dataset (if a column name 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'], ...]

[Source]

     # File lib/sequel/dataset/actions.rb, line 383
383:     def map(column=nil, &block)
384:       if column
385:         raise(Error, ARG_BLOCK_ERROR_MSG) if block
386:         return naked.map(column) if row_proc
387:         if column.is_a?(Array)
388:           super(){|r| r.values_at(*column)}
389:         else
390:           super(){|r| r[column]}
391:         end
392:       else
393:         super(&block)
394:       end
395:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 404
404:     def max(column=Sequel.virtual_row(&Proc.new))
405:       aggregate_dataset.get{max(column).as(:max)}
406:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 415
415:     def min(column=Sequel.virtual_row(&Proc.new))
416:       aggregate_dataset.get{min(column).as(:min)}
417:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 431
431:     def multi_insert(hashes, opts=OPTS)
432:       return if hashes.empty?
433:       columns = hashes.first.keys
434:       import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
435:     end

Yields each row in the dataset, but interally uses multiple queries as needed with limit and offset 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 make sure that all rows in the dataset are yielded and none are yielded twice, the dataset must have an unambiguous order. Sequel requires that datasets using this method have an order, but it cannot ensure that the order is unambiguous.

Options:

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 450
450:     def paged_each(opts=OPTS)
451:       unless @opts[:order]
452:         raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
453:       end
454: 
455:       total_limit = @opts[:limit]
456:       offset = @opts[:offset] || 0
457: 
458:       if server = @opts[:server]
459:         opts = opts.merge(:server=>server)
460:       end
461: 
462:       rows_per_fetch = opts[:rows_per_fetch] || 1000
463:       num_rows_yielded = rows_per_fetch
464:       total_rows = 0
465: 
466:       db.transaction(opts) do
467:         while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
468:           if total_limit && total_rows + rows_per_fetch > total_limit
469:             rows_per_fetch = total_limit - total_rows
470:           end
471: 
472:           num_rows_yielded = 0
473:           limit(rows_per_fetch, offset).each do |row|
474:             num_rows_yielded += 1
475:             total_rows += 1 if total_limit
476:             yield row
477:           end
478: 
479:           offset += rows_per_fetch
480:         end
481:       end
482: 
483:       self
484:     end

Create a named prepared statement that is stored in the database (and connection) for reuse.

[Source]

     # File lib/sequel/adapters/jdbc.rb, line 677
677:       def prepare(type, name=nil, *values)
678:         ps = to_prepared_statement(type, values)
679:         ps.extend(PreparedStatementMethods)
680:         if name
681:           ps.prepared_statement_name = name
682:           db.set_prepared_statement(name, ps)
683:         end
684:         ps
685:       end

Prepare the given type of query with the given name and store it in the database. Note that a new native prepared statement is created on each call to this prepared statement.

[Source]

     # File lib/sequel/adapters/sqlite.rb, line 379
379:       def prepare(type, name=nil, *values)
380:         ps = to_prepared_statement(type, values)
381:         ps.extend(PreparedStatementMethods)
382:         if name
383:           ps.prepared_statement_name = name
384:           db.set_prepared_statement(name, ps)
385:         end
386:         ps
387:       end

Returns a Range instance made from the minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.

  DB[:table].range(:id) # SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1
  # => 1..10
  DB[:table].interval{function(column)} # SELECT max(function(column)) AS v1, min(function(column)) AS v2 FROM table LIMIT 1
  # => 0..7

[Source]

     # File lib/sequel/dataset/actions.rb, line 493
493:     def range(column=Sequel.virtual_row(&Proc.new))
494:       if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first
495:         (r[:v1]..r[:v2])
496:       end
497:     end

Returns a hash with key_column values as keys and value_column values as values. Similar to to_hash, but only selects the columns given.

  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 * 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. Usually you can do this by calling the as method on the expression and providing an alias.

[Source]

     # File lib/sequel/dataset/actions.rb, line 514
514:     def select_hash(key_column, value_column)
515:       _select_hash(:to_hash, key_column, value_column)
516:     end

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.

  DB[:table].select_hash(: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([:first, :middle], [:last, :id]) # SELECT * 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. Usually you can do this by calling the as method on the expression and providing an alias.

[Source]

     # File lib/sequel/dataset/actions.rb, line 533
533:     def select_hash_groups(key_column, value_column)
534:       _select_hash(:to_hash_groups, key_column, value_column)
535:     end

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. Usually you can do this by calling the as method on the expression and providing an alias.

[Source]

     # File lib/sequel/dataset/actions.rb, line 557
557:     def select_map(column=nil, &block)
558:       _select_map(column, false, &block)
559:     end

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. Usually you can do this by calling the as method on the expression and providing an alias.

[Source]

     # File lib/sequel/dataset/actions.rb, line 577
577:     def select_order_map(column=nil, &block)
578:       _select_map(column, true, &block)
579:     end

Returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method.

[Source]

     # File lib/sequel/dataset/actions.rb, line 584
584:     def single_record
585:       clone(:limit=>1).each{|r| return r}
586:       nil
587:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 592
592:     def single_value
593:       if r = ungraphed.naked.single_record
594:         r.values.first
595:       end
596:     end

Makes each yield arrays of rows, with each array containing the rows for a given result set. Does not work with graphing. So you can submit SQL with multiple statements and easily determine which statement returned which results.

Modifies the row_proc of the returned dataset so that it still works as expected (running on the hashes instead of on the arrays of hashes). If you modify the row_proc afterward, note that it will receive an array of hashes instead of a hash.

[Source]

     # File lib/sequel/adapters/mysql.rb, line 333
333:       def split_multiple_result_sets
334:         raise(Error, "Can't split multiple statements on a graphed dataset") if opts[:graph]
335:         ds = clone(:split_multiple_result_sets=>true)
336:         ds.row_proc = proc{|x| x.map{|h| row_proc.call(h)}} if row_proc
337:         ds
338:       end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 605
605:     def sum(column=Sequel.virtual_row(&Proc.new))
606:       aggregate_dataset.get{sum(column).as(:sum)}
607:     end

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

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

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 628
628:     def to_hash(key_column, value_column = nil)
629:       h = {}
630:       if value_column
631:         return naked.to_hash(key_column, value_column) if row_proc
632:         if value_column.is_a?(Array)
633:           if key_column.is_a?(Array)
634:             each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
635:           else
636:             each{|r| h[r[key_column]] = r.values_at(*value_column)}
637:           end
638:         else
639:           if key_column.is_a?(Array)
640:             each{|r| h[r.values_at(*key_column)] = r[value_column]}
641:           else
642:             each{|r| h[r[key_column]] = r[value_column]}
643:           end
644:         end
645:       elsif key_column.is_a?(Array)
646:         each{|r| h[r.values_at(*key_column)] = r}
647:       else
648:         each{|r| h[r[key_column]] = r}
649:       end
650:       h
651:     end

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

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

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 671
671:     def to_hash_groups(key_column, value_column = nil)
672:       h = {}
673:       if value_column
674:         return naked.to_hash_groups(key_column, value_column) if row_proc
675:         if value_column.is_a?(Array)
676:           if key_column.is_a?(Array)
677:             each{|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
678:           else
679:             each{|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
680:           end
681:         else
682:           if key_column.is_a?(Array)
683:             each{|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
684:           else
685:             each{|r| (h[r[key_column]] ||= []) << r[value_column]}
686:           end
687:         end
688:       elsif key_column.is_a?(Array)
689:         each{|r| (h[r.values_at(*key_column)] ||= []) << r}
690:       else
691:         each{|r| (h[r[key_column]] ||= []) << r}
692:       end
693:       h
694:     end

Truncates the dataset. Returns nil.

  DB[:table].truncate # TRUNCATE table
  # => nil

[Source]

     # File lib/sequel/dataset/actions.rb, line 700
700:     def truncate
701:       execute_ddl(truncate_sql)
702:     end

Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent. values should 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=>:x+1, :y=>0) # UPDATE table SET x = (x + 1), y = 0
  # => 10

[Source]

     # File lib/sequel/dataset/actions.rb, line 714
714:     def update(values=OPTS, &block)
715:       sql = update_sql(values)
716:       if uses_returning?(:update)
717:         returning_fetch_rows(sql, &block)
718:       else
719:         execute_dui(sql)
720:       end
721:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 726
726:     def with_sql_delete(sql)
727:       execute_dui(sql)
728:     end

Protected Instance methods

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 735
735:     def _import(columns, values, opts)
736:       trans_opts = opts.merge(:server=>@opts[:server])
737:       if opts[:return] == :primary_key
738:         @db.transaction(trans_opts){values.map{|v| insert(columns, v)}}
739:       else
740:         stmts = multi_insert_sql(columns, values)
741:         @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}}
742:       end
743:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 746
746:     def _select_map_multiple(ret_cols)
747:       map{|r| r.values_at(*ret_cols)}
748:     end

Returns an array of the first value in each row.

[Source]

     # File lib/sequel/dataset/actions.rb, line 751
751:     def _select_map_single
752:       map{|r| r.values.first}
753:     end