Class | Sequel::Dataset

In:

lib/sequel/adapters/do.rb
lib/sequel/adapters/jdbc.rb
lib/sequel/adapters/mysql.rb
lib/sequel/adapters/postgres.rb
lib/sequel/adapters/sqlite.rb
lib/sequel/adapters/utils/stored_procedures.rb
lib/sequel/adapters/swift.rb
lib/sequel/dataset.rb
lib/sequel/dataset/actions.rb
lib/sequel/dataset/features.rb
lib/sequel/dataset/graph.rb
lib/sequel/dataset/misc.rb
lib/sequel/dataset/prepared_statements.rb
lib/sequel/dataset/query.rb
lib/sequel/dataset/sql.rb
lib/sequel/dataset/mutation.rb
lib/sequel/extensions/pagination.rb
lib/sequel/extensions/pretty_table.rb
lib/sequel/extensions/query.rb
lib/sequel/extensions/to_dot.rb
lib/sequel/extensions/columns_introspection.rb

Parent: | Sequel::Dataset

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.

### Contents

- 2 - Methods that execute code on the database
- 4 - Methods that describe what the dataset supports
- 5 - Methods related to dataset graphing
- 6 - Miscellaneous methods
- 8 - Methods related to prepared statements or bound variables
- 1 - Methods that return modified datasets
- 3 - User Methods relating to SQL Creation
- 9 - Internal Methods relating to SQL Creation
- 7 - Mutation methods

### Methods

<< == [] []= _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 call case_expression_sql_append cast_sql_append clause_methods clone column_all_sql_append columns columns! columns_without_introspection complex_expression_sql_append compound_clone compound_from_self constant_sql_append count def_append_methods def_mutation_method def_mutation_method delete delete delete_sql distinct each each_page each_server empty? eql? except exclude exclude_having exclude_where exists fetch_rows fetch_rows fetch_rows fetch_rows fetch_rows fetch_rows fetch_rows filter first first_source first_source_alias first_source_table for_update from from_self function_sql_append get graph graph grep group group_and_count group_by hash having identifier_input_method identifier_output_method import insert insert insert_multiple insert_sql inspect intersect interval introspect_all_columns 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 negative_boolean_constant_sql_append new options_overlap or order order_append order_by order_more order_prepend ordered_expression_sql_append paginate placeholder_literal_string_sql_append prepare prepare prepare prepare prepared_arg_placeholder print provides_accurate_rows_matched? qualified_identifier_sql_append qualify qualify_to qualify_to_first_source query quote_identifier_append quote_identifiers? quote_schema_table_append quoted_identifier_append range recursive_cte_requires_column_aliases? replace 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_map select_more select_order_map select_sql server set set_defaults set_graph_aliases set_overrides simple_select_all? single_record single_value split_alias split_multiple_result_sets sql subscript_sql_append sum supports_cte? supports_cte_in_subqueries? supports_distinct_on? 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_returning? supports_select_all_and_column? supports_timestamp_timezones? supports_timestamp_usecs? supports_where_true? supports_window_functions? to_csv to_dot to_hash to_prepared_statement truncate truncate_sql unbind unfiltered ungraphed ungrouped union unlimited unordered unused_table_alias update update update_sql use_cursor where window_function_sql_append window_sql_append with with_recursive with_sql

### Included Modules

StoredProcedures Sequel::MySQL::DatasetMethods Sequel::MySQL::PreparedStatements::DatasetMethods Sequel::Postgres::DatasetMethods ::Sequel::SQLite::DatasetMethods Metaprogramming Enumerable SQL::AliasMethods SQL::BooleanMethods SQL::CastMethods SQL::ComplexExpressionMethods SQL::InequalityMethods SQL::NumericMethods SQL::OrderMethods SQL::StringMethods ColumnsIntrospection

### Classes and Modules

Module Sequel::Dataset::ArgumentMapper
Module Sequel::Dataset::BindArgumentMethods
Module Sequel::Dataset::PreparedStatementMethods
Module Sequel::Dataset::StoredProcedureMethods
Module Sequel::Dataset::StoredProcedures
Class Sequel::Dataset::TYPE_TRANSLATOR

### Constants

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[]
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)
DatasetClass | = | self
DatasetClass | = | self
PREPARED_ARG_PLACEHOLDER | = | LiteralString.new('$').freeze
DatasetClass | = | self
PREPARED_ARG_PLACEHOLDER | = | ':'.freeze
DatasetClass | = | self

### 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

call(type, bind_vars={}, *values, &block)

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

[Source]

         # File lib/sequel/adapters/postgres.rb, line 585
    585:         def call(type, bind_vars={}, *values, &block)
    586:           ps = to_prepared_statement(type, values)
    587:           ps.extend(BindArgumentMethods)
    588:           ps.call(bind_vars, &block)
    589:         end

call(type, bind_vars={}, *values, &block)

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

[Source]

         # File lib/sequel/adapters/sqlite.rb, line 288
    288:       def call(type, bind_vars={}, *values, &block)
    289:         ps = to_prepared_statement(type, values)
    290:         ps.extend(BindArgumentMethods)
    291:         ps.call(bind_vars, &block)
    292:       end

delete()

Delete rows matching this dataset

[Source]

         # File lib/sequel/adapters/mysql.rb, line 270
    270:       def delete
    271:         execute_dui(delete_sql){|c| return c.affected_rows}
    272:       end

fetch_rows(sql) {|row| ...}

Yield a hash for each row in the dataset.

[Source]

         # File lib/sequel/adapters/sqlite.rb, line 295
    295:       def fetch_rows(sql)
    296:         execute(sql) do |result|
    297:           i = -1
    298:           cps = db.conversion_procs
    299:           type_procs = result.types.map{|t| cps[base_type_name(t)]}
    300:           cols = result.columns.map{|c| i+=1; [output_identifier(c), i, type_procs[i]]}
    301:           @columns = cols.map{|c| c.first}
    302:           result.each do |values|
    303:             row = {}
    304:             cols.each do |name,i,type_proc|
    305:               v = values[i]
    306:               if type_proc && v.is_a?(String)
    307:                 v = type_proc.call(v)
    308:               end
    309:               row[name] = v
    310:             end
    311:             yield row
    312:           end
    313:         end
    314:       end

fetch_rows(sql) {|h| ...}

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

[Source]

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

fetch_rows(sql, &block)

Set the columns and yield the hashes to the block.

[Source]

         # File lib/sequel/adapters/swift.rb, line 138
    138:       def fetch_rows(sql, &block)
    139:         execute(sql) do |res|
    140:           @columns = res.fields
    141:           res.each(&block)
    142:         end
    143:         self
    144:       end

fetch_rows(sql, &block)

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

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 592
    592:       def fetch_rows(sql, &block)
    593:         execute(sql){|result| process_result_set(result, &block)}
    594:         self
    595:       end

fetch_rows(sql, &block)

Yield all rows returned by executing the given SQL and converting the types.

[Source]

         # File lib/sequel/adapters/postgres.rb, line 466
    466:       def fetch_rows(sql, &block)
    467:         return cursor_fetch_rows(sql, &block) if @opts[:cursor]
    468:         execute(sql){|res| yield_hash_rows(res, fetch_rows_set_cols(res), &block)}
    469:       end

fetch_rows(sql) {|s| ...}

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 277
    277:       def fetch_rows(sql, &block)
    278:         execute(sql) do |r|
    279:           i = -1
    280:           cps = db.conversion_procs
    281:           cols = r.fetch_fields.map do |f|
    282:             # Pretend tinyint is another integer type if its length is not 1, to
    283:             # avoid casting to boolean if Sequel::MySQL.convert_tinyint_to_bool
    284:             # is set.
    285:             type_proc = f.type == 1 && f.length != 1 ? cps[2] : cps[f.type]
    286:             [output_identifier(f.name), type_proc, i+=1]
    287:           end
    288:           @columns = cols.map{|c| c.first}
    289:           if opts[:split_multiple_result_sets]
    290:             s = []
    291:             yield_rows(r, cols){|h| s << h}
    292:             yield s
    293:           else
    294:             yield_rows(r, cols, &block)
    295:           end
    296:         end
    297:         self
    298:       end

graph(*)

Don‘t allow graphing a dataset that splits multiple statements

[Source]

         # File lib/sequel/adapters/mysql.rb, line 301
    301:       def graph(*)
    302:         raise(Error, "Can't graph a dataset that splits multiple result sets") if opts[:split_multiple_result_sets]
    303:         super
    304:       end

insert(*values)

Insert a new value into this dataset

[Source]

         # File lib/sequel/adapters/mysql.rb, line 307
    307:       def insert(*values)
    308:         execute_dui(insert_sql(*values)){|c| return c.insert_id}
    309:       end

prepare(type, name=nil, *values)

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 319
    319:       def prepare(type, name=nil, *values)
    320:         ps = to_prepared_statement(type, values)
    321:         ps.extend(PreparedStatementMethods)
    322:         if name
    323:           ps.prepared_statement_name = name
    324:           db.prepared_statements[name] = ps
    325:         end
    326:         ps
    327:       end

prepare(type, name=nil, *values)

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

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 599
    599:       def prepare(type, name=nil, *values)
    600:         ps = to_prepared_statement(type, values)
    601:         ps.extend(PreparedStatementMethods)
    602:         if name
    603:           ps.prepared_statement_name = name
    604:           db.prepared_statements[name] = ps
    605:         end
    606:         ps
    607:       end

prepare(type, name=nil, *values)

Prepare the given type of statement with the given name, and store it in the database to be called later.

[Source]

         # File lib/sequel/adapters/postgres.rb, line 593
    593:         def prepare(type, name=nil, *values)
    594:           ps = to_prepared_statement(type, values)
    595:           ps.extend(PreparedStatementMethods)
    596:           if name
    597:             ps.prepared_statement_name = name
    598:             db.prepared_statements[name] = ps
    599:           end
    600:           ps
    601:         end

prepared_arg_placeholder()

PostgreSQL uses $N for placeholders instead of ?, so use a $ as the placeholder.

[Source]

         # File lib/sequel/adapters/postgres.rb, line 607
    607:         def prepared_arg_placeholder
    608:           PREPARED_ARG_PLACEHOLDER
    609:         end

replace(*args)

Replace (update or insert) the matching row.

[Source]

         # File lib/sequel/adapters/mysql.rb, line 312
    312:       def replace(*args)
    313:         execute_dui(replace_sql(*args)){|c| return c.insert_id}
    314:       end

split_multiple_result_sets()

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 325
    325:       def split_multiple_result_sets
    326:         raise(Error, "Can't split multiple statements on a graphed dataset") if opts[:graph]
    327:         ds = clone(:split_multiple_result_sets=>true)
    328:         ds.row_proc = proc{|x| x.map{|h| row_proc.call(h)}} if row_proc
    329:         ds
    330:       end

update(values={})

Update the matching rows.

[Source]

         # File lib/sequel/adapters/mysql.rb, line 333
    333:       def update(values={})
    334:         execute_dui(update_sql(values)){|c| return c.affected_rows}
    335:       end

use_cursor(opts={})

Uses a cursor for fetching records, instead of fetching the entire result set at once. Can be used to process large datasets without holding all rows in memory (which is what the underlying drivers do by default). Options:

- :rows_per_fetch - the number of rows per fetch (default 1000). Higher numbers result in fewer queries but greater memory use.

Usage:

      DB[:huge_table].use_cursor.each{|row| p row}
      DB[:huge_table].use_cursor(:rows_per_fetch=>10000).each{|row| p row}

This is untested with the prepared statement/bound variable support, and unlikely to work with either.

[Source]

         # File lib/sequel/adapters/postgres.rb, line 486
    486:       def use_cursor(opts={})
    487:         clone(:cursor=>{:rows_per_fetch=>1000}.merge(opts))
    488:       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 get import insert insert_multiple interval last map max min multi_insert range select_hash select_map select_order_map set single_record single_value sum to_csv to_hash truncate update METHS ).split.map{|x| x.to_sym}

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

### Public Instance methods

<<(arg)

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

      DB[:items] << {:id=>0, :name=>'Zero'} << DB[:old_items].select(:id, name)

[Source]

        # File lib/sequel/dataset/actions.rb, line 23
    23:     def <<(arg)
    24:       insert(arg)
    25:       self
    26:     end

[](*conditions)

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 32
    32:     def [](*conditions)
    33:       raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
    34:       first(*conditions)
    35:     end

[]=(conditions, values)

Update all records matching the conditions with the values specified. Returns the number of rows affected.

      DB[:table][:id=>1] = {:id=>2} # UPDATE table SET id = 2 WHERE id = 1
      # => 1 # number of rows affected

[Source]

        # File lib/sequel/dataset/actions.rb, line 42
    42:     def []=(conditions, values)
    43:       filter(conditions).update(values)
    44:     end

all(&block)

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

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

      # Iterate over all rows in the table
      DB[:table].all{|row| p row}

[Source]

        # File lib/sequel/dataset/actions.rb, line 54
    54:     def all(&block)
    55:       a = []
    56:       each{|r| a << r}
    57:       post_load(a)
    58:       a.each(&block) if block
    59:       a
    60:     end

avg(column)

Returns the average value for the given column.

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

[Source]

        # File lib/sequel/dataset/actions.rb, line 66
    66:     def avg(column)
    67:       aggregate_dataset.get{avg(column)}
    68:     end

columns()

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

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

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

[Source]

        # File lib/sequel/dataset/actions.rb, line 79
    79:     def columns
    80:       return @columns if @columns
    81:       ds = unfiltered.unordered.clone(:distinct => nil, :limit => 1, :offset=>nil)
    82:       ds.each{break}
    83:       @columns = ds.instance_variable_get(:@columns)
    84:       @columns || []
    85:     end

columns!()

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

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

[Source]

        # File lib/sequel/dataset/actions.rb, line 92
    92:     def columns!
    93:       @columns = nil
    94:       columns
    95:     end

count()

Returns the number of records in the dataset.

      DB[:table].count # SELECT COUNT(*) AS count FROM table LIMIT 1
      # => 3

[Source]

         # File lib/sequel/dataset/actions.rb, line 101
    101:     def count
    102:       aggregate_dataset.get{COUNT(:*){}.as(count)}.to_i
    103:     end

delete(&block)

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 110
    110:     def delete(&block)
    111:       sql = delete_sql
    112:       if uses_returning?(:delete)
    113:         returning_fetch_rows(sql, &block)
    114:       else
    115:         execute_dui(sql)
    116:       end
    117:     end

each() {|row_proc.call(r)}| ...}

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 128
    128:     def each(&block)
    129:       if @opts[:graph]
    130:         graph_each(&block)
    131:       elsif row_proc = @row_proc
    132:         fetch_rows(select_sql){|r| yield row_proc.call(r)}
    133:       else
    134:         fetch_rows(select_sql, &block)
    135:       end
    136:       self
    137:     end

empty?()

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

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 143
    143:     def empty?
    144:       get(1).nil?
    145:     end

fetch_rows(sql)

Executes a select query and fetches records, yielding each record to the supplied block. The yielded records should be hashes with symbol keys. This method should probably should not be called by user code, use `each` instead.

[Source]

         # File lib/sequel/dataset/actions.rb, line 151
    151:     def fetch_rows(sql)
    152:       raise NotImplemented, NOTIMPL_MSG
    153:     end

first(*args, &block)

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. 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 185
    185:     def first(*args, &block)
    186:       ds = block ? filter(&block) : self
    187:
    188:       if args.empty?
    189:         ds.single_record
    190:       else
    191:         args = (args.size == 1) ? args.first : args
    192:         if Integer === args
    193:           ds.limit(args).all
    194:         else
    195:           ds.filter(args).single_record
    196:         end
    197:       end
    198:     end

get(column=nil, &block)

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

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

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 208
    208:     def get(column=nil, &block)
    209:       if column
    210:         raise(Error, ARG_BLOCK_ERROR_MSG) if block
    211:         select(column).single_value
    212:       else
    213:         select(&block).single_value
    214:       end
    215:     end

import(columns, values, opts={})

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

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

The method also accepts a :slice or :commit_every option that specifies the number of records to insert per transaction. This is useful especially when inserting a large number of records, e.g.:

      # this will commit every 50 records
      dataset.import([:x, :y], [[1, 2], [3, 4], ...], :slice => 50)

[Source]

         # File lib/sequel/dataset/actions.rb, line 239
    239:     def import(columns, values, opts={})
    240:       return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)
    241:
    242:       return if values.empty?
    243:       raise(Error, IMPORT_ERROR_MSG) if columns.empty?
    244:
    245:       if slice_size = opts[:commit_every] || opts[:slice]
    246:         offset = 0
    247:         loop do
    248:           @db.transaction(opts){multi_insert_sql(columns, values[offset, slice_size]).each{|st| execute_dui(st)}}
    249:           offset += slice_size
    250:           break if offset >= values.length
    251:         end
    252:       else
    253:         statements = multi_insert_sql(columns, values)
    254:         @db.transaction{statements.each{|st| execute_dui(st)}}
    255:       end
    256:     end

insert(*values, &block)

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 293
    293:     def insert(*values, &block)
    294:       sql = insert_sql(*values)
    295:       if uses_returning?(:insert)
    296:         returning_fetch_rows(sql, &block)
    297:       else
    298:         execute_insert(sql)
    299:       end
    300:     end

insert_multiple(array, &block)

Inserts multiple values. If a block is given it is invoked for each item in the given array before inserting it. See `multi_insert` as a possible faster version that inserts multiple records in one SQL statement.

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

      DB[:table].insert_multiple([{:x=>1}, {:x=>2}]){|row| row[:y] = row[:x] * 2}
      # INSERT INTO table (x, y) VALUES (1, 2)
      # INSERT INTO table (x, y) VALUES (2, 4)

[Source]

         # File lib/sequel/dataset/actions.rb, line 314
    314:     def insert_multiple(array, &block)
    315:       if block
    316:         array.each {|i| insert(block[i])}
    317:       else
    318:         array.each {|i| insert(i)}
    319:       end
    320:     end

interval(column)

Returns the interval between minimum and maximum values for the given column.

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 327
    327:     def interval(column)
    328:       aggregate_dataset.get{max(column) - min(column)}
    329:     end

last(*args, &block)

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

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

      DB[:table].order(:id.desc).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2
      # => [{:id=>1}, {:id=>2}]

[Source]

         # File lib/sequel/dataset/actions.rb, line 341
    341:     def last(*args, &block)
    342:       raise(Error, 'No order specified') unless @opts[:order]
    343:       reverse.first(*args, &block)
    344:     end

map(column=nil, &block)

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 360
    360:     def map(column=nil, &block)
    361:       if column
    362:         raise(Error, ARG_BLOCK_ERROR_MSG) if block
    363:         return naked.map(column) if row_proc
    364:         if column.is_a?(Array)
    365:           super(){|r| r.values_at(*column)}
    366:         else
    367:           super(){|r| r[column]}
    368:         end
    369:       else
    370:         super(&block)
    371:       end
    372:     end

max(column)

Returns the maximum value for the given column.

      DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1
      # => 10

[Source]

         # File lib/sequel/dataset/actions.rb, line 378
    378:     def max(column)
    379:       aggregate_dataset.get{max(column)}
    380:     end

min(column)

Returns the minimum value for the given column.

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 386
    386:     def min(column)
    387:       aggregate_dataset.get{min(column)}
    388:     end

multi_insert(hashes, opts={})

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

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

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

You can also use the :slice or :commit_every option that import accepts.

[Source]

         # File lib/sequel/dataset/actions.rb, line 402
    402:     def multi_insert(hashes, opts={})
    403:       return if hashes.empty?
    404:       columns = hashes.first.keys
    405:       import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
    406:     end

range(column)

Returns a `Range` instance made from the minimum and maximum values for the given column.

      DB[:table].range(:id) # SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1
      # => 1..10

[Source]

         # File lib/sequel/dataset/actions.rb, line 413
    413:     def range(column)
    414:       if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first
    415:         (r[:v1]..r[:v2])
    416:       end
    417:     end

select_hash(key_column, value_column)

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

      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'], ...}

[Source]

         # File lib/sequel/dataset/actions.rb, line 430
    430:     def select_hash(key_column, value_column)
    431:       if key_column.is_a?(Array)
    432:         if value_column.is_a?(Array)
    433:           select(*(key_column + value_column)).to_hash(key_column.map{|c| hash_key_symbol(c)}, value_column.map{|c| hash_key_symbol(c)})
    434:         else
    435:           select(*(key_column + [value_column])).to_hash(key_column.map{|c| hash_key_symbol(c)}, hash_key_symbol(value_column))
    436:         end
    437:       elsif value_column.is_a?(Array)
    438:         select(key_column, *value_column).to_hash(hash_key_symbol(key_column), value_column.map{|c| hash_key_symbol(c)})
    439:       else
    440:         select(key_column, value_column).to_hash(hash_key_symbol(key_column), hash_key_symbol(value_column))
    441:       end
    442:     end

select_map(column=nil, &block)

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

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

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

You can also provide an array of column names:

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 460
    460:     def select_map(column=nil, &block)
    461:       _select_map(column, false, &block)
    462:     end

select_order_map(column=nil, &block)

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

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

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

You can also provide an array of column names:

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 477
    477:     def select_order_map(column=nil, &block)
    478:       _select_map(column, true, &block)
    479:     end

set(*args)

Alias for update, but not aliased directly so subclasses don‘t have to override both methods.

[Source]

         # File lib/sequel/dataset/actions.rb, line 483
    483:     def set(*args)
    484:       update(*args)
    485:     end

single_record()

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 490
    490:     def single_record
    491:       clone(:limit=>1).each{|r| return r}
    492:       nil
    493:     end

single_value()

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 498
    498:     def single_value
    499:       if r = naked.ungraphed.single_record
    500:         r.values.first
    501:       end
    502:     end

sum(column)

Returns the sum for the given column.

      DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1
      # => 55

[Source]

         # File lib/sequel/dataset/actions.rb, line 508
    508:     def sum(column)
    509:       aggregate_dataset.get{sum(column)}
    510:     end

to_csv(include_column_titles = true)

Returns a string in CSV format containing the dataset records. By default the CSV representation includes the column titles in the first line. You can turn that off by passing false as the include_column_titles argument.

This does not use a CSV library or handle quoting of values in any way. If any values in any of the rows could include commas or line endings, you shouldn‘t use this.

      puts DB[:table].to_csv # SELECT * FROM table
      # id,name
      # 1,Jim
      # 2,Bob

[Source]

         # File lib/sequel/dataset/actions.rb, line 525
    525:     def to_csv(include_column_titles = true)
    526:       n = naked
    527:       cols = n.columns
    528:       csv = ''
    529:       csv << "#{cols.join(COMMA_SEPARATOR)}\r\n" if include_column_titles
    530:       n.each{|r| csv << "#{cols.collect{|c| r[c]}.join(COMMA_SEPARATOR)}\r\n"}
    531:       csv
    532:     end

to_hash(key_column, value_column = nil)

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 553
    553:     def to_hash(key_column, value_column = nil)
    554:       h = {}
    555:       if value_column
    556:         return naked.to_hash(key_column, value_column) if row_proc
    557:         if value_column.is_a?(Array)
    558:           if key_column.is_a?(Array)
    559:             each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
    560:           else
    561:             each{|r| h[r[key_column]] = r.values_at(*value_column)}
    562:           end
    563:         else
    564:           if key_column.is_a?(Array)
    565:             each{|r| h[r.values_at(*key_column)] = r[value_column]}
    566:           else
    567:             each{|r| h[r[key_column]] = r[value_column]}
    568:           end
    569:         end
    570:       elsif key_column.is_a?(Array)
    571:         each{|r| h[r.values_at(*key_column)] = r}
    572:       else
    573:         each{|r| h[r[key_column]] = r}
    574:       end
    575:       h
    576:     end

truncate()

Truncates the dataset. Returns nil.

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 582
    582:     def truncate
    583:       execute_ddl(truncate_sql)
    584:     end

update(values={}, &block)

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 596
    596:     def update(values={}, &block)
    597:       sql = update_sql(values)
    598:       if uses_returning?(:update)
    599:         returning_fetch_rows(sql, &block)
    600:       else
    601:         execute_dui(sql)
    602:       end
    603:     end

### Protected Instance methods

_select_map_multiple(ret_cols)

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

[Source]

         # File lib/sequel/dataset/actions.rb, line 608
    608:     def _select_map_multiple(ret_cols)
    609:       map{|r| r.values_at(*ret_cols)}
    610:     end

_select_map_single()

Returns an array of the first value in each row.

[Source]

         # File lib/sequel/dataset/actions.rb, line 613
    613:     def _select_map_single
    614:       map{|r| r.values.first}
    615:     end

## 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

provides_accurate_rows_matched?()

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 23
    23:     def provides_accurate_rows_matched?
    24:       true
    25:     end

quote_identifiers?()

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:       elsif db.respond_to?(:quote_identifiers?)
    14:         @quote_identifiers = db.quote_identifiers?
    15:       else
    16:         @quote_identifiers = false
    17:       end
    18:     end

recursive_cte_requires_column_aliases?()

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

[Source]

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

requires_placeholder_type_specifiers?()

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

[Source]

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

requires_sql_standard_datetimes?()

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

[Source]

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

supports_cte?(type=:select)

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 48
    48:     def supports_cte?(type=:select)
    49:       send("#{type}_clause_methods""#{type}_clause_methods").include?("#{type}_with_sql""#{type}_with_sql")
    50:     end

supports_cte_in_subqueries?()

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 55
    55:     def supports_cte_in_subqueries?
    56:       false
    57:     end

supports_distinct_on?()

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

[Source]

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

supports_insert_select?()

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 66
    66:     def supports_insert_select?
    67:       supports_returning?(:insert)
    68:     end

supports_intersect_except?()

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

[Source]

        # File lib/sequel/dataset/features.rb, line 71
    71:     def supports_intersect_except?
    72:       true
    73:     end

supports_intersect_except_all?()

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

[Source]

        # File lib/sequel/dataset/features.rb, line 76
    76:     def supports_intersect_except_all?
    77:       true
    78:     end

supports_is_true?()

Whether the dataset supports the IS TRUE syntax.

[Source]

        # File lib/sequel/dataset/features.rb, line 81
    81:     def supports_is_true?
    82:       true
    83:     end

supports_join_using?()

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

[Source]

        # File lib/sequel/dataset/features.rb, line 86
    86:     def supports_join_using?
    87:       true
    88:     end

supports_modifying_joins?()

Whether modifying joined datasets is supported.

[Source]

        # File lib/sequel/dataset/features.rb, line 91
    91:     def supports_modifying_joins?
    92:       false
    93:     end

supports_multiple_column_in?()

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

[Source]

        # File lib/sequel/dataset/features.rb, line 97
    97:     def supports_multiple_column_in?
    98:       true
    99:     end

supports_ordered_distinct_on?()

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

[Source]

         # File lib/sequel/dataset/features.rb, line 103
    103:     def supports_ordered_distinct_on?
    104:       supports_distinct_on?
    105:     end

supports_returning?(type)

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 109
    109:     def supports_returning?(type)
    110:       send("#{type}_clause_methods""#{type}_clause_methods").include?("#{type}_returning_sql""#{type}_returning_sql")
    111:     end

supports_select_all_and_column?()

Whether the database supports SELECT *, column FROM table

[Source]

         # File lib/sequel/dataset/features.rb, line 114
    114:     def supports_select_all_and_column?
    115:       true
    116:     end

supports_timestamp_timezones?()

Whether the dataset supports timezones in literal timestamps

[Source]

         # File lib/sequel/dataset/features.rb, line 119
    119:     def supports_timestamp_timezones?
    120:       false
    121:     end

supports_timestamp_usecs?()

Whether the dataset supports fractional seconds in literal timestamps

[Source]

         # File lib/sequel/dataset/features.rb, line 124
    124:     def supports_timestamp_usecs?
    125:       true
    126:     end

supports_where_true?()

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 135
    135:     def supports_where_true?
    136:       true
    137:     end

supports_window_functions?()

Whether the dataset supports window functions.

[Source]

         # File lib/sequel/dataset/features.rb, line 129
    129:     def supports_window_functions?
    130:       false
    131:     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

add_graph_aliases(graph_aliases)

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

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

[Source]

        # File lib/sequel/dataset/graph.rb, line 17
    17:     def add_graph_aliases(graph_aliases)
    18:       columns, graph_aliases = graph_alias_columns(graph_aliases)
    19:       ds = select_more(*columns)
    20:       ds.opts[:graph_aliases] = (ds.opts[:graph_aliases] || (ds.opts[:graph][:column_aliases] rescue {}) || {}).merge(graph_aliases)
    21:       ds
    22:     end

graph(dataset, join_conditions = nil, options = {}, &block)

Allows you to join multiple datasets/tables and have the result set split into component tables.

This differs from the usual usage of join, which returns the result set as a single hash. For example:

      # CREATE TABLE artists (id INTEGER, name TEXT);
      # CREATE TABLE albums (id INTEGER, name TEXT, artist_id INTEGER);

      DB[:artists].left_outer_join(:albums, :artist_id=>:id).first
      #=> {:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id}

      DB[:artists].graph(:albums, :artist_id=>:id).first
      #=> {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>{:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id}}

Using a join such as left_outer_join, the attribute names that are shared between the tables are combined in the single return hash. You can get around that by using `select` with correct aliases for all of the columns, but it is simpler to use `graph` and have the result set split for you. In addition, `graph` respects any `row_proc` of the current dataset and the datasets you use with `graph`.

If you are graphing a table and all columns for that table are nil, this indicates that no matching rows existed in the table, so graph will return nil instead of a hash with all nil values:

      # If the artist doesn't have any albums
      DB[:artists].graph(:albums, :artist_id=>:id).first
      => {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>nil}

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

set_graph_aliases(graph_aliases)

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

graph_aliases :

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

      DB[:artists].graph(:albums, :artist_id=>:id).
        set_graph_aliases(:name=>:artists,
                          :album_name=>[:albums, :name],
                          :forty_two=>[:albums, :fourtwo, 42]).first
      # SELECT artists.name, albums.name AS album_name, 42 AS forty_two ...
      # => {:artists=>{:name=>artists.name}, :albums=>{:name=>albums.name, :fourtwo=>42}}

[Source]

         # File lib/sequel/dataset/graph.rb, line 230
    230:     def set_graph_aliases(graph_aliases)
    231:       columns, graph_aliases = graph_alias_columns(graph_aliases)
    232:       ds = select(*columns)
    233:       ds.opts[:graph_aliases] = graph_aliases
    234:       ds
    235:     end

ungraphed()

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 239
    239:     def ungraphed
    240:       clone(:graph=>nil, :graph_aliases=>nil)
    241:     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 | [RW] | The database related to this dataset. This is the Database instance that will execute all of this dataset‘s queries.
opts | [RW] | The hash of options for this dataset, keys are symbols.

### Public Class methods

new(db, opts = nil)

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, opts = nil)
    29:       @db = db
    30:       @opts = opts || {}
    31:     end

### Public Instance methods

==(o)

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

each_server() {|server(s)}| ...}

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

eql?(o)

Alias for ==

[Source]

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

first_source()

Alias of `first_source_alias`

[Source]

        # File lib/sequel/dataset/misc.rb, line 54
    54:     def first_source
    55:       first_source_alias
    56:     end

first_source_alias()

The first source (primary table) for this dataset. If the dataset doesn‘t have a table, raises an `Error`. If the table is aliased, returns the aliased name.

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

      DB[:table___t].first_source_alias
      # => :t

[Source]

        # File lib/sequel/dataset/misc.rb, line 66
    66:     def first_source_alias
    67:       source = @opts[:from]
    68:       if source.nil? || source.empty?
    69:         raise Error, 'No source specified for query'
    70:       end
    71:       case s = source.first
    72:       when SQL::AliasedExpression
    73:         s.aliaz
    74:       when Symbol
    75:         sch, table, aliaz = split_symbol(s)
    76:         aliaz ? aliaz.to_sym : s
    77:       else
    78:         s
    79:       end
    80:     end

first_source_table()

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

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

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

[Source]

         # File lib/sequel/dataset/misc.rb, line 91
     91:     def first_source_table
     92:       source = @opts[:from]
     93:       if source.nil? || source.empty?
     94:         raise Error, 'No source specified for query'
     95:       end
     96:       case s = source.first
     97:       when SQL::AliasedExpression
     98:         s.expression
     99:       when Symbol
    100:         sch, table, aliaz = split_symbol(s)
    101:         aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
    102:       else
    103:         s
    104:       end
    105:     end

hash()

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 109
    109:     def hash
    110:       [db, opts.sort_by{|k, v| k.to_s}, sql].hash
    111:     end

identifier_input_method()

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

[Source]

         # File lib/sequel/dataset/misc.rb, line 115
    115:     def identifier_input_method
    116:       if defined?(@identifier_input_method)
    117:         @identifier_input_method
    118:       elsif db.respond_to?(:identifier_input_method)
    119:         @identifier_input_method = db.identifier_input_method
    120:       else
    121:         @identifier_input_method = nil
    122:       end
    123:     end

identifier_output_method()

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

[Source]

         # File lib/sequel/dataset/misc.rb, line 127
    127:     def identifier_output_method
    128:       if defined?(@identifier_output_method)
    129:         @identifier_output_method
    130:       elsif db.respond_to?(:identifier_output_method)
    131:         @identifier_output_method = db.identifier_output_method
    132:       else
    133:         @identifier_output_method = nil
    134:       end
    135:     end

inspect()

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 139
    139:     def inspect
    140:       c = self.class
    141:       c = c.superclass while c.name.nil? || c.name == ''
    142:       "#<#{c.name}: #{sql.inspect}>"
    143:     end

row_number_column()

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 147
    147:     def row_number_column
    148:       :x_sequel_row_number_x
    149:     end

split_alias(c)

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

[Source]

         # File lib/sequel/dataset/misc.rb, line 154
    154:     def split_alias(c)
    155:       case c
    156:       when Symbol
    157:         c_table, column, aliaz = split_symbol(c)
    158:         [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
    159:       when SQL::AliasedExpression
    160:         [c.expression, c.aliaz]
    161:       when SQL::JoinClause
    162:         [c.table, c.table_alias]
    163:       else
    164:         [c, nil]
    165:       end
    166:     end

unused_table_alias(table_alias, used_aliases = [])

Creates a unique table alias that hasn‘t already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with "_N" if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.

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

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

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

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

      DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2])
      # => :table_3

[Source]

         # File lib/sequel/dataset/misc.rb, line 190
    190:     def unused_table_alias(table_alias, used_aliases = [])
    191:       table_alias = alias_symbol(table_alias)
    192:       used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
    193:       used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
    194:       if used_aliases.include?(table_alias)
    195:         i = 0
    196:         loop do
    197:           ta = "#{table_alias}_#{i}""#{table_alias}_#{i}"
    198:           return ta unless used_aliases.include?(ta)
    199:           i += 1
    200:         end
    201:       else
    202:         table_alias
    203:       end
    204:     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.

### Classes and Modules

Module Sequel::Dataset::UnnumberedArgumentMapper

### Constants

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

### Public Instance methods

bind(bind_vars={})

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 210
    210:     def bind(bind_vars={})
    211:       clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars)
    212:     end

call(type, bind_variables={}, *values, &block)

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 221
    221:     def call(type, bind_variables={}, *values, &block)
    222:       prepare(type, nil, *values).call(bind_variables, &block)
    223:     end

prepare(type, name=nil, *values)

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 243
    243:     def prepare(type, name=nil, *values)
    244:       ps = to_prepared_statement(type, values)
    245:       db.prepared_statements[name] = ps if name
    246:       ps
    247:     end

### Protected Instance methods

to_prepared_statement(type, values=nil)

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 253
    253:     def to_prepared_statement(type, values=nil)
    254:       ps = bind
    255:       ps.extend(PreparedStatementMethods)
    256:       ps.orig_dataset = self
    257:       ps.prepared_type = type
    258:       ps.prepared_modify_values = values
    259:       ps
    260:     end

## 1 - Methods that return modified datasets

These methods all return modified copies of the receiver.

### Constants

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 Instance methods

and(*cond, &block)

Adds an further filter to an existing filter using AND. If no filter exists an error is raised. This method is identical to filter except it expects an existing filter.

      DB[:table].filter(:a).and(:b) # SELECT * FROM table WHERE a AND b

[Source]

        # File lib/sequel/dataset/query.rb, line 46
    46:     def and(*cond, &block)
    47:       raise(InvalidOperation, "No existing filter found.") unless @opts[:having] || @opts[:where]
    48:       filter(*cond, &block)
    49:     end

clone(opts = {})

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 55
    55:     def clone(opts = {})
    56:       c = super()
    57:       c.opts = @opts.merge(opts)
    58:       c.instance_variable_set(:@columns, nil) if opts.keys.any?{|o| COLUMN_CHANGE_OPTS.include?(o)}
    59:       c
    60:     end

distinct(*args)

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 71
    71:     def distinct(*args)
    72:       raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on?
    73:       clone(:distinct => args)
    74:     end

except(dataset, opts={})

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

:alias : | Use the given value as the from_self alias
:all : | Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur
:from_self : | Set to false to not wrap the returned dataset in a from_self, use with care.

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

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

      DB[:items].except(DB[:other_items], :alias=>:i)
      # SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i

[Source]

        # File lib/sequel/dataset/query.rb, line 93
    93:     def except(dataset, opts={})
    94:       opts = {:all=>opts} unless opts.is_a?(Hash)
    95:       raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
    96:       raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
    97:       compound_clone(:except, dataset, opts)
    98:     end

exclude(*cond, &block)

Performs the inverse of Dataset#filter. 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 108
    108:     def exclude(*cond, &block)
    109:       _filter_or_exclude(true, @opts[:having] ? :having : :where, *cond, &block)
    110:     end

exclude_having(*cond, &block)

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

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

[Source]

         # File lib/sequel/dataset/query.rb, line 116
    116:     def exclude_having(*cond, &block)
    117:       _filter_or_exclude(true, :having, *cond, &block)
    118:     end

exclude_where(*cond, &block)

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

      DB[:items].select_group(:name).exclude_where(:category => 'software')
      # SELECT * FROM items WHERE (category != 'software')

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

[Source]

         # File lib/sequel/dataset/query.rb, line 130
    130:     def exclude_where(*cond, &block)
    131:       _filter_or_exclude(true, :where, *cond, &block)
    132:     end

filter(*cond, &block)

Returns a copy of the dataset with the given conditions imposed upon it. If the query already has a HAVING clause, then the conditions are imposed in the HAVING clause. If not, then they are imposed in the WHERE clause.

filter 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.

filter also takes 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].filter(:id => 3)
      # SELECT * FROM items WHERE (id = 3)

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

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

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

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

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

Multiple filter calls can be chained for scoping:

      software = dataset.filter(:category => 'software').filter{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 186
    186:     def filter(*cond, &block)
    187:       _filter(@opts[:having] ? :having : :where, *cond, &block)
    188:     end

for_update()

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 193
    193:     def for_update
    194:       lock_style(:update)
    195:     end

from(*source)

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

      DB[:items].from # SQL: SELECT *
      DB[:items].from(:blah) # SQL: SELECT * FROM blah
      DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo

[Source]

         # File lib/sequel/dataset/query.rb, line 204
    204:     def from(*source)
    205:       table_alias_num = 0
    206:       sources = []
    207:       ctes = nil
    208:       source.each do |s|
    209:         case s
    210:         when Hash
    211:           s.each{|k,v| sources << SQL::AliasedExpression.new(k,v)}
    212:         when Dataset
    213:           if hoist_cte?(s)
    214:             ctes ||= []
    215:             ctes += s.opts[:with]
    216:             s = s.clone(:with=>nil)
    217:           end
    218:           sources << SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
    219:         when Symbol
    220:           sch, table, aliaz = split_symbol(s)
    221:           if aliaz
    222:             s = sch ? SQL::QualifiedIdentifier.new(sch.to_sym, table.to_sym) : SQL::Identifier.new(table.to_sym)
    223:             sources << SQL::AliasedExpression.new(s, aliaz.to_sym)
    224:           else
    225:             sources << s
    226:           end
    227:         else
    228:           sources << s
    229:         end
    230:       end
    231:       o = {:from=>sources.empty? ? nil : sources}
    232:       o[:with] = (opts[:with] || []) + ctes if ctes
    233:       o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
    234:       clone(o)
    235:     end

from_self(opts={})

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 248
    248:     def from_self(opts={})
    249:       fs = {}
    250:       @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)}
    251:       clone(fs).from(opts[:alias] ? as(opts[:alias]) : self)
    252:     end

grep(columns, patterns, opts={})

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 285
    285:     def grep(columns, patterns, opts={})
    286:       if opts[:all_patterns]
    287:         conds = Array(patterns).map do |pat|
    288:           SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
    289:         end
    290:         filter(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds))
    291:       else
    292:         conds = Array(columns).map do |c|
    293:           SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
    294:         end
    295:         filter(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds))
    296:       end
    297:     end

group(*columns, &block)

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

      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 306
    306:     def group(*columns, &block)
    307:       virtual_row_columns(columns, block)
    308:       clone(:group => (columns.compact.empty? ? nil : columns))
    309:     end

group_and_count(*columns, &block)

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

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 337
    337:     def group_and_count(*columns, &block)
    338:       select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT)
    339:     end

group_by(*columns, &block)

Alias of group

[Source]

         # File lib/sequel/dataset/query.rb, line 312
    312:     def group_by(*columns, &block)
    313:       group(*columns, &block)
    314:     end

having(*cond, &block)

Returns a copy of the dataset with the HAVING conditions changed. See filter 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 345
    345:     def having(*cond, &block)
    346:       _filter(:having, *cond, &block)
    347:     end

intersect(dataset, opts={})

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

:alias : | Use the given value as the from_self alias
:all : | Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur
:from_self : | Set to false to not wrap the returned dataset in a from_self, use with care.

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

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

      DB[:items].intersect(DB[:other_items], :alias=>:i)
      # SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i

[Source]

         # File lib/sequel/dataset/query.rb, line 366
    366:     def intersect(dataset, opts={})
    367:       opts = {:all=>opts} unless opts.is_a?(Hash)
    368:       raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
    369:       raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
    370:       compound_clone(:intersect, dataset, opts)
    371:     end

invert()

Inverts the current filter.

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

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

[Source]

         # File lib/sequel/dataset/query.rb, line 380
    380:     def invert
    381:       having, where = @opts[:having], @opts[:where]
    382:       raise(Error, "No current filter") unless having || where
    383:       o = {}
    384:       o[:having] = SQL::BooleanExpression.invert(having) if having
    385:       o[:where] = SQL::BooleanExpression.invert(where) if where
    386:       clone(o)
    387:     end

join(*args, &block)

Alias of `inner_join`

[Source]

         # File lib/sequel/dataset/query.rb, line 390
    390:     def join(*args, &block)
    391:       inner_join(*args, &block)
    392:     end

join_table(type, table, expr=nil, options={}) {|table_name, last_alias, @opts[:join] || []| ...}

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:
  - Dataset - a subselect is performed with an alias of tN for some value of N
  - Model (or anything responding to :table_name) - table.table_name
  - String, Symbol: table
- 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 filter, 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.
- 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 `filter`, 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|
        (:d.qualify(ta) > :e.qualify(jta)) & {:f.qualify(ta)=>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 445
    445:     def join_table(type, table, expr=nil, options={}, &block)
    446:       if hoist_cte?(table)
    447:         s, ds = hoist_cte(table)
    448:         return s.join_table(type, ds, expr, options, &block)
    449:       end
    450:
    451:       using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
    452:       if using_join && !supports_join_using?
    453:         h = {}
    454:         expr.each{|s| h[s] = s}
    455:         return join_table(type, table, h, options)
    456:       end
    457:
    458:       case options
    459:       when Hash
    460:         table_alias = options[:table_alias]
    461:         last_alias = options[:implicit_qualifier]
    462:       when Symbol, String, SQL::Identifier
    463:         table_alias = options
    464:         last_alias = nil
    465:       else
    466:         raise Error, "invalid options format for join_table: #{options.inspect}"
    467:       end
    468:
    469:       if Dataset === table
    470:         if table_alias.nil?
    471:           table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
    472:           table_alias = dataset_alias(table_alias_num)
    473:         end
    474:         table_name = table_alias
    475:       else
    476:         table = table.table_name if table.respond_to?(:table_name)
    477:         table, implicit_table_alias = split_alias(table)
    478:         table_alias ||= implicit_table_alias
    479:         table_name = table_alias || table
    480:       end
    481:
    482:       join = if expr.nil? and !block
    483:         SQL::JoinClause.new(type, table, table_alias)
    484:       elsif using_join
    485:         raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
    486:         SQL::JoinUsingClause.new(expr, type, table, table_alias)
    487:       else
    488:         last_alias ||= @opts[:last_joined_table] || first_source_alias
    489:         if Sequel.condition_specifier?(expr)
    490:           expr = expr.collect do |k, v|
    491:             k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
    492:             v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
    493:             [k,v]
    494:           end
    495:           expr = SQL::BooleanExpression.from_value_pairs(expr)
    496:         end
    497:         if block
    498:           expr2 = yield(table_name, last_alias, @opts[:join] || [])
    499:           expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
    500:         end
    501:         SQL::JoinOnClause.new(expr, type, table, table_alias)
    502:       end
    503:
    504:       opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name}
    505:       opts[:num_dataset_sources] = table_alias_num if table_alias_num
    506:       clone(opts)
    507:     end

limit(l, o = nil)

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

      DB[:items].limit(10) # SELECT * FROM items LIMIT 10
      DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20
      DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10
      DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10
      DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20

[Source]

         # File lib/sequel/dataset/query.rb, line 526
    526:     def limit(l, o = nil)
    527:       return from_self.limit(l, o) if @opts[:sql]
    528:
    529:       if Range === l
    530:         o = l.first
    531:         l = l.last - l.first + (l.exclude_end? ? 0 : 1)
    532:       end
    533:       l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
    534:       if l.is_a?(Integer)
    535:         raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
    536:       end
    537:       opts = {:limit => l}
    538:       if o
    539:         o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
    540:         if o.is_a?(Integer)
    541:           raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
    542:         end
    543:         opts[:offset] = o
    544:       end
    545:       clone(opts)
    546:     end

lock_style(style)

Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. Otherwise, a symbol may be used for database independent locking. Currently :update is respected by most databases, and :share is supported by some.

      DB[:items].lock_style('FOR SHARE') # SELECT * FROM items FOR SHARE

[Source]

         # File lib/sequel/dataset/query.rb, line 554
    554:     def lock_style(style)
    555:       clone(:lock => style)
    556:     end

naked()

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 564
    564:     def naked
    565:       ds = clone
    566:       ds.row_proc = nil
    567:       ds
    568:     end

or(*cond, &block)

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

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

[Source]

         # File lib/sequel/dataset/query.rb, line 574
    574:     def or(*cond, &block)
    575:       clause = (@opts[:having] ? :having : :where)
    576:       raise(InvalidOperation, "No existing filter found.") unless @opts[clause]
    577:       cond = cond.first if cond.size == 1
    578:       clone(clause => SQL::BooleanExpression.new(:OR, @opts[clause], filter_expr(cond, &block)))
    579:     end

order(*columns, &block)

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

      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('a + b'.lit) # SELECT * FROM items ORDER BY a + b
      DB[:items].order(:a + :b) # SELECT * FROM items ORDER BY (a + b)
      DB[:items].order(:name.desc) # SELECT * FROM items ORDER BY name DESC
      DB[:items].order(:name.asc(: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 595
    595:     def order(*columns, &block)
    596:       virtual_row_columns(columns, block)
    597:       clone(:order => (columns.compact.empty?) ? nil : columns)
    598:     end

order_append(*columns, &block)

Alias of order_more, for naming consistency with order_prepend.

[Source]

         # File lib/sequel/dataset/query.rb, line 601
    601:     def order_append(*columns, &block)
    602:       order_more(*columns, &block)
    603:     end

order_by(*columns, &block)

Alias of order

[Source]

         # File lib/sequel/dataset/query.rb, line 606
    606:     def order_by(*columns, &block)
    607:       order(*columns, &block)
    608:     end

order_more(*columns, &block)

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

      DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
      DB[:items].order(:a).order_more(:b) # SELECT * FROM items ORDER BY a, b

[Source]

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

order_prepend(*columns, &block)

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

      DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
      DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a

[Source]

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

qualify(table=first_source)

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

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

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

[Source]

         # File lib/sequel/dataset/query.rb, line 637
    637:     def qualify(table=first_source)
    638:       qualify_to(table)
    639:     end

qualify_to(table)

Return a copy of the dataset with unqualified identifiers in the SELECT, WHERE, GROUP, HAVING, and ORDER clauses qualified by the given table. If no columns are currently selected, select all columns of the given table.

      DB[:items].filter(:id=>1).qualify_to(:i)
      # SELECT i.* FROM items WHERE (i.id = 1)

[Source]

         # File lib/sequel/dataset/query.rb, line 648
    648:     def qualify_to(table)
    649:       o = @opts
    650:       return clone if o[:sql]
    651:       h = {}
    652:       (o.keys & QUALIFY_KEYS).each do |k|
    653:         h[k] = qualified_expression(o[k], table)
    654:       end
    655:       h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty?
    656:       clone(h)
    657:     end

qualify_to_first_source()

Qualify the dataset to its current first source. This is useful if you have unqualified identifiers in the query that all refer to the first source, and you want to join to another table which has columns with the same name as columns in the current dataset. See `qualify_to`.

      DB[:items].filter(:id=>1).qualify_to_first_source
      # SELECT items.* FROM items WHERE (items.id = 1)

[Source]

         # File lib/sequel/dataset/query.rb, line 667
    667:     def qualify_to_first_source
    668:       qualify_to(first_source)
    669:     end

returning(*values)

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

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

[Source]

         # File lib/sequel/dataset/query.rb, line 679
    679:     def returning(*values)
    680:       clone(:returning=>values)
    681:     end

reverse(*order)

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].order(:id).reverse # SELECT * FROM items ORDER BY id DESC
      DB[:items].order(:id).reverse(:name.asc) # SELECT * FROM items ORDER BY name ASC

[Source]

         # File lib/sequel/dataset/query.rb, line 689
    689:     def reverse(*order)
    690:       order(*invert_order(order.empty? ? @opts[:order] : order))
    691:     end

reverse_order(*order)

Alias of `reverse`

[Source]

         # File lib/sequel/dataset/query.rb, line 694
    694:     def reverse_order(*order)
    695:       reverse(*order)
    696:     end

select(*columns, &block)

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

      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 705
    705:     def select(*columns, &block)
    706:       virtual_row_columns(columns, block)
    707:       m = []
    708:       columns.each do |i|
    709:         i.is_a?(Hash) ? m.concat(i.map{|k, v| SQL::AliasedExpression.new(k,v)}) : m << i
    710:       end
    711:       clone(:select => m)
    712:     end

select_all(*tables)

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

      DB[:items].select(:a).select_all # SELECT * FROM items
      DB[:items].select_all(:items) # SELECT items.* FROM items
      DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items

[Source]

         # File lib/sequel/dataset/query.rb, line 721
    721:     def select_all(*tables)
    722:       if tables.empty?
    723:         clone(:select => nil)
    724:       else
    725:         select(*tables.map{|t| i, a = split_alias(t); a || i}.map{|t| SQL::ColumnAll.new(t)})
    726:       end
    727:     end

select_append(*columns, &block)

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

      DB[:items].select(:a).select(:b) # SELECT b FROM items
      DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items
      DB[:items].select_append(:b) # SELECT *, b FROM items

[Source]

         # File lib/sequel/dataset/query.rb, line 736
    736:     def select_append(*columns, &block)
    737:       cur_sel = @opts[:select]
    738:       if !cur_sel || cur_sel.empty?
    739:         unless supports_select_all_and_column?
    740:           return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_more(*columns, &block)
    741:         end
    742:         cur_sel = [WILDCARD]
    743:       end
    744:       select(*(cur_sel + columns), &block)
    745:     end

select_group(*columns, &block)

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

      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 756
    756:     def select_group(*columns, &block)
    757:       virtual_row_columns(columns, block)
    758:       select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
    759:     end

select_more(*columns, &block)

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

      DB[:items].select(:a).select(:b) # SELECT b FROM items
      DB[:items].select(:a).select_more(:b) # SELECT a, b FROM items
      DB[:items].select_more(:b) # SELECT b FROM items

[Source]

         # File lib/sequel/dataset/query.rb, line 768
    768:     def select_more(*columns, &block)
    769:       columns = @opts[:select] + columns if @opts[:select]
    770:       select(*columns, &block)
    771:     end

server(servr)

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

      DB[:items].all # Uses the :read_only or :default server
      DB[:items].delete # Uses the :default server
      DB[:items].server(:blah).delete # Uses the :blah server

[Source]

         # File lib/sequel/dataset/query.rb, line 782
    782:     def server(servr)
    783:       clone(:server=>servr)
    784:     end

set_defaults(hash)

Set the default values for insert and update statements. The values hash passed to insert or update are merged into this hash, so any values in the hash passed to insert or update will override values passed to this method.

      DB[:items].set_defaults(:a=>'a', :c=>'c').insert(:a=>'d', :b=>'b')
      # INSERT INTO items (a, c, b) VALUES ('d', 'c', 'b')

[Source]

         # File lib/sequel/dataset/query.rb, line 792
    792:     def set_defaults(hash)
    793:       clone(:defaults=>(@opts[:defaults]||{}).merge(hash))
    794:     end

set_overrides(hash)

Set values that override hash arguments given to insert and update statements. This hash is merged into the hash provided to insert or update, so values will override any values given in the insert/update hashes.

      DB[:items].set_overrides(:a=>'a', :c=>'c').insert(:a=>'d', :b=>'b')
      # INSERT INTO items (a, c, b) VALUES ('a', 'c', 'b')

[Source]

         # File lib/sequel/dataset/query.rb, line 802
    802:     def set_overrides(hash)
    803:       clone(:overrides=>hash.merge(@opts[:overrides]||{}))
    804:     end

unbind()

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].filter(: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 816
    816:     def unbind
    817:       u = Unbinder.new
    818:       ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join]))
    819:       [ds, u.binds]
    820:     end

unfiltered()

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

      DB[:items].group(:a).having(:a=>1).where(:b).unfiltered
      # SELECT * FROM items GROUP BY a

[Source]

         # File lib/sequel/dataset/query.rb, line 826
    826:     def unfiltered
    827:       clone(:where => nil, :having => nil)
    828:     end

ungrouped()

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

      DB[:items].group(:a).having(:a=>1).where(:b).ungrouped
      # SELECT * FROM items WHERE b

[Source]

         # File lib/sequel/dataset/query.rb, line 834
    834:     def ungrouped
    835:       clone(:group => nil, :having => nil)
    836:     end

union(dataset, opts={})

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

:alias : | Use the given value as the from_self alias
:all : | Set to true to use UNION ALL instead of UNION, so duplicate rows can occur
:from_self : | Set to false to not wrap the returned dataset in a from_self, use with care.

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

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

      DB[:items].union(DB[:other_items], :alias=>:i)
      # SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i

[Source]

         # File lib/sequel/dataset/query.rb, line 854
    854:     def union(dataset, opts={})
    855:       opts = {:all=>opts} unless opts.is_a?(Hash)
    856:       compound_clone(:union, dataset, opts)
    857:     end

unlimited()

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 862
    862:     def unlimited
    863:       clone(:limit=>nil, :offset=>nil)
    864:     end

unordered()

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 869
    869:     def unordered
    870:       order(nil)
    871:     end

where(*cond, &block)

Add a condition to the WHERE clause. See `filter` for argument types.

      DB[:items].group(:a).having(:a).filter(:b)
      # SELECT * FROM items GROUP BY a HAVING a AND b

      DB[:items].group(:a).having(:a).where(:b)
      # SELECT * FROM items WHERE b GROUP BY a HAVING a

[Source]

         # File lib/sequel/dataset/query.rb, line 880
    880:     def where(*cond, &block)
    881:       _filter(:where, *cond, &block)
    882:     end

with(name, dataset, opts={})

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

:args : | Specify the arguments/columns for the CTE, should be an array of symbols.
:recursive : | Specify that this is a recursive CTE

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

[Source]

         # File lib/sequel/dataset/query.rb, line 892
    892:     def with(name, dataset, opts={})
    893:       raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
    894:       if hoist_cte?(dataset)
    895:         s, ds = hoist_cte(dataset)
    896:         s.with(name, ds, opts)
    897:       else
    898:         clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)])
    899:       end
    900:     end

with_recursive(name, nonrecursive, recursive, opts={})

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

:args : | Specify the arguments/columns for the CTE, should be an array of symbols.
:union_all : | Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts.

      DB[:t].select(:i___id, :pi___parent_id).
       with_recursive(:t,
                      DB[:i1].filter(:parent_id=>nil),
                      DB[:t].join(:t, :i=>:parent_id).select(:i1__id, :i1__parent_id),
                      :args=>[:i, :pi])
      # WITH RECURSIVE t(i, pi) AS (
      #   SELECT * FROM i1 WHERE (parent_id IS NULL)
      #   UNION ALL
      #   SELECT i1.id, i1.parent_id FROM t INNER JOIN t ON (t.i = t.parent_id)
      # )
      # SELECT i AS id, pi AS parent_id FROM t

[Source]

         # File lib/sequel/dataset/query.rb, line 919
    919:     def with_recursive(name, nonrecursive, recursive, opts={})
    920:       raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
    921:       if hoist_cte?(nonrecursive)
    922:         s, ds = hoist_cte(nonrecursive)
    923:         s.with_recursive(name, ds, recursive, opts)
    924:       elsif hoist_cte?(recursive)
    925:         s, ds = hoist_cte(recursive)
    926:         s.with_recursive(name, nonrecursive, ds, opts)
    927:       else
    928:         clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))])
    929:       end
    930:     end

with_sql(sql, *args)

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

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

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

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

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

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

[Source]

         # File lib/sequel/dataset/query.rb, line 944
    944:     def with_sql(sql, *args)
    945:       if sql.is_a?(Symbol)
    946:         sql = send(sql, *args)
    947:       else
    948:         sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
    949:       end
    950:       clone(:sql=>sql)
    951:     end

### Protected Instance methods

compound_clone(type, dataset, opts)

Add the dataset to the list of compounds

[Source]

         # File lib/sequel/dataset/query.rb, line 956
    956:     def compound_clone(type, dataset, opts)
    957:       if hoist_cte?(dataset)
    958:         s, ds = hoist_cte(dataset)
    959:         return s.compound_clone(type, ds, opts)
    960:       end
    961:       ds = compound_from_self.clone(:compounds=>Array(@opts[:compounds]).map{|x| x.dup} + [[type, dataset.compound_from_self, opts[:all]]])
    962:       opts[:from_self] == false ? ds : ds.from_self(opts)
    963:     end

options_overlap(opts)

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

[Source]

         # File lib/sequel/dataset/query.rb, line 966
    966:     def options_overlap(opts)
    967:       !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty?
    968:     end

simple_select_all?()

Whether this dataset is a simple SELECT * FROM table.

[Source]

         # File lib/sequel/dataset/query.rb, line 971
    971:     def simple_select_all?
    972:       o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)}
    973:       o.length == 1 && (f = o[:from]) && f.length == 1 && (f.first.is_a?(Symbol) || f.first.is_a?(SQL::AliasedExpression))
    974:     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

delete_sql()

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

exists()

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:       LiteralString.new("EXISTS (#{select_sql})")
    24:     end

insert_sql(*values)

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:           vals = @opts[:defaults].merge(vals) if @opts[:defaults]
    44:           vals = vals.merge(@opts[:overrides]) if @opts[:overrides]
    45:           values = []
    46:           vals.each do |k,v|
    47:             columns << k
    48:             values << v
    49:           end
    50:         when Dataset, Array, LiteralString
    51:           values = vals
    52:         else
    53:           if vals.respond_to?(:values) && (v = vals.values).is_a?(Hash)
    54:             return insert_sql(v)
    55:           end
    56:         end
    57:       when 2
    58:         if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
    59:           columns, values = v0, v1
    60:           raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
    61:         end
    62:       end
    63:
    64:       if values.is_a?(Array) && values.empty? && !insert_supports_empty_values?
    65:         columns = [columns().last]
    66:         values = ['DEFAULT'.lit]
    67:       end
    68:       clone(:columns=>columns, :values=>values)._insert_sql
    69:     end

literal_append(sql, v)

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

multi_insert_sql(columns, values)

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

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 131
    131:     def multi_insert_sql(columns, values)
    132:       values.map{|r| insert_sql(columns, r)}
    133:     end

select_sql()

Returns a SELECT SQL query string.

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 138
    138:     def select_sql
    139:       return static_sql(@opts[:sql]) if @opts[:sql]
    140:       clause_sql(:select)
    141:     end

sql()

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 144
    144:     def sql
    145:       select_sql
    146:     end

truncate_sql()

Returns a TRUNCATE SQL query string. See `truncate`

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 151
    151:     def truncate_sql
    152:       if opts[:sql]
    153:         static_sql(opts[:sql])
    154:       else
    155:         check_modification_allowed!
    156:         raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where]
    157:         _truncate_sql(source_list(opts[:from]))
    158:       end
    159:     end

update_sql(values = {})

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 168
    168:     def update_sql(values = {})
    169:       return static_sql(opts[:sql]) if opts[:sql]
    170:       check_modification_allowed!
    171:       clone(:values=>values)._update_sql
    172:     end

## 9 - Internal Methods relating to SQL Creation

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

### Constants

ALL | = | ' ALL'.freeze
AND_SEPARATOR | = | " AND ".freeze
APOS | = | "'".freeze
APOS_RE | = | /'/.freeze
ARRAY_EMPTY | = | '(NULL)'.freeze
AS | = | ' AS '.freeze
ASC | = | ' ASC'.freeze
BACKSLASH_RE | = | /\\/.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
COLUMN_ALL | = | '.*'.freeze
COLUMN_REF_RE1 | = | /\A((?:(?!__).)+)__((?:(?!___).)+)___(.+)\z/.freeze
COLUMN_REF_RE2 | = | /\A((?:(?!___).)+)___(.+)\z/.freeze
COLUMN_REF_RE3 | = | /\A((?:(?!__).)+)__(.+)\z/.freeze
COMMA | = | ', '.freeze
COMMA_SEPARATOR | = | COMMA
CONDITION_FALSE | = | '(1 = 0)'.freeze
CONDITION_TRUE | = | '(1 = 1)'.freeze
COUNT_FROM_SELF_OPTS | = | [:distinct, :group, :sql, :limit, :compounds]
COUNT_OF_ALL_AS_COUNT | = | SQL::Function.new(:count, LiteralString.new('*'.freeze)).as(:count)
DATASET_ALIAS_BASE_NAME | = | 't'.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
EXTRACT | = | 'extract('.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
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
QUAD_BACKSLASH | = | "\\\\\\\\".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
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
UNDERSCORE | = | '_'.freeze
UPDATE | = | 'UPDATE'.freeze
UPDATE_CLAUSE_METHODS | = | clause_methods(:update, %w'update table set where')
USING | = | ' USING ('.freeze
VALUES | = | " VALUES ".freeze
WHERE | = | " WHERE ".freeze
WILDCARD | = | LiteralString.new('*').freeze

PUBLIC_APPEND_METHODS

=

(<<-END).split.map{|x| x.to_sym} literal aliased_expression_sql array_sql boolean_constant_sql case_expression_sql cast_sql column_all_sql complex_expression_sql constant_sql function_sql join_clause_sql join_on_clause_sql join_using_clause_sql negative_boolean_constant_sql ordered_expression_sql placeholder_literal_string_sql qualified_identifier_sql quote_identifier quote_schema_table quoted_identifier subscript_sql window_sql window_function_sql END ).split.map{|x| x.to_sym}

PRIVATE_APPEND_METHODS | = | (<<-END).split.map{|x| x.to_sym} argument_list as_sql column_list compound_dataset_sql expression_list literal_array literal_blob literal_dataset literal_expression literal_hash literal_other literal_string literal_symbol source_list subselect_sql table_ref END ).split.map{|x| x.to_sym}

### Public Class methods

clause_methods(type, clauses)

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 181
    181:     def self.clause_methods(type, clauses)
    182:       clauses.map{|clause| "#{type}_#{clause}_sql""#{type}_#{clause}_sql"}.freeze
    183:     end

def_append_methods(meths)

[Source]

         # File lib/sequel/dataset/sql.rb, line 327
    327:     def self.def_append_methods(meths)
    328:       meths.each do |meth|
    329:         class_eval("def \#{meth}(*args, &block)\ns = ''\n\#{meth}_append(s, *args, &block)\ns\nend\n", __FILE__, __LINE__ + 1)
    330:       end
    331:     end

### Public Instance methods

aliased_expression_sql_append(sql, ae)

SQL fragment for AliasedExpression

[Source]

         # File lib/sequel/dataset/sql.rb, line 343
    343:     def aliased_expression_sql_append(sql, ae)
    344:       literal_append(sql, ae.expression)
    345:       as_sql_append(sql, ae.aliaz)
    346:     end

array_sql_append(sql, a)

SQL fragment for Array

[Source]

         # File lib/sequel/dataset/sql.rb, line 349
    349:     def array_sql_append(sql, a)
    350:       if a.empty?
    351:         sql << ARRAY_EMPTY
    352:       else
    353:         sql << PAREN_OPEN
    354:         expression_list_append(sql, a)
    355:         sql << PAREN_CLOSE
    356:       end
    357:     end

boolean_constant_sql_append(sql, constant)

SQL fragment for BooleanConstants

[Source]

         # File lib/sequel/dataset/sql.rb, line 360
    360:     def boolean_constant_sql_append(sql, constant)
    361:       if (constant == true || constant == false) && !supports_where_true?
    362:         sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE)
    363:       else
    364:         literal_append(sql, constant)
    365:       end
    366:     end

case_expression_sql_append(sql, ce)

SQL fragment for CaseExpression

[Source]

         # File lib/sequel/dataset/sql.rb, line 369
    369:     def case_expression_sql_append(sql, ce)
    370:       sql << CASE_OPEN
    371:       if ce.expression?
    372:         sql << SPACE
    373:         literal_append(sql, ce.expression)
    374:       end
    375:       w = CASE_WHEN
    376:       t = CASE_THEN
    377:       ce.conditions.each do |c,r|
    378:         sql << w
    379:         literal_append(sql, c)
    380:         sql << t
    381:         literal_append(sql, r)
    382:       end
    383:       sql << CASE_ELSE
    384:       literal_append(sql, ce.default)
    385:       sql << CASE_END
    386:     end

cast_sql_append(sql, expr, type)

SQL fragment for the SQL CAST expression

[Source]

         # File lib/sequel/dataset/sql.rb, line 389
    389:     def cast_sql_append(sql, expr, type)
    390:       sql << CAST_OPEN
    391:       literal_append(sql, expr)
    392:       sql << AS << db.cast_type_literal(type).to_s
    393:       sql << PAREN_CLOSE
    394:     end

column_all_sql_append(sql, ca)

SQL fragment for specifying all columns in a given table

[Source]

         # File lib/sequel/dataset/sql.rb, line 397
    397:     def column_all_sql_append(sql, ca)
    398:       quote_schema_table_append(sql, ca.table)
    399:       sql << COLUMN_ALL
    400:     end

complex_expression_sql_append(sql, op, args)

[Source]

         # File lib/sequel/dataset/sql.rb, line 402
    402:     def complex_expression_sql_append(sql, op, args)
    403:       case op
    404:       when *IS_OPERATORS
    405:         r = args.at(1)
    406:         if r.nil? || supports_is_true?
    407:           raise(InvalidOperation, 'Invalid argument used for IS operator') unless v = IS_LITERALS[r]
    408:           sql << PAREN_OPEN
    409:           literal_append(sql, args.at(0))
    410:           sql << SPACE << op.to_s << SPACE
    411:           sql << v << PAREN_CLOSE
    412:         elsif op == :IS
    413:           complex_expression_sql_append(sql, "=""=", args)
    414:         else
    415:           complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new("!=""!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)])
    416:         end
    417:       when :IN, "NOT IN""NOT IN"
    418:         cols = args.at(0)
    419:         vals = args.at(1)
    420:         col_array = true if cols.is_a?(Array)
    421:         if vals.is_a?(Array)
    422:           val_array = true
    423:           empty_val_array = vals == []
    424:         end
    425:         if col_array
    426:           if empty_val_array
    427:             if op == :IN
    428:               literal_append(sql, SQL::BooleanExpression.from_value_pairs(cols.to_a.map{|x| [x, x]}, :AND, true))
    429:             else
    430:               literal_append(sql, 1=>1)
    431:             end
    432:           elsif !supports_multiple_column_in?
    433:             if val_array
    434:               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]})})
    435:               literal_append(sql, op == :IN ? expr : ~expr)
    436:             else
    437:               old_vals = vals
    438:               vals = vals.naked if vals.is_a?(Sequel::Dataset)
    439:               vals = vals.to_a
    440:               val_cols = old_vals.columns
    441:               complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
    442:             end
    443:           else
    444:             # If the columns and values are both arrays, use array_sql instead of
    445:             # literal so that if values is an array of two element arrays, it
    446:             # will be treated as a value list instead of a condition specifier.
    447:             sql << PAREN_OPEN
    448:             literal_append(sql, cols)
    449:             sql << SPACE << op.to_s << SPACE
    450:             if val_array
    451:               array_sql_append(sql, vals)
    452:             else
    453:               literal_append(sql, vals)
    454:             end
    455:             sql << PAREN_CLOSE
    456:           end
    457:         else
    458:           if empty_val_array
    459:             if op == :IN
    460:               literal_append(sql, SQL::BooleanExpression.from_value_pairs([[cols, cols]], :AND, true))
    461:             else
    462:               literal_append(sql, 1=>1)
    463:             end
    464:           else
    465:             sql << PAREN_OPEN
    466:             literal_append(sql, cols)
    467:             sql << SPACE << op.to_s << SPACE
    468:             literal_append(sql, vals)
    469:             sql << PAREN_CLOSE
    470:           end
    471:         end
    472:       when *TWO_ARITY_OPERATORS
    473:         sql << PAREN_OPEN
    474:         literal_append(sql, args.at(0))
    475:         sql << SPACE << op.to_s << SPACE
    476:         literal_append(sql, args.at(1))
    477:         sql << PAREN_CLOSE
    478:       when *N_ARITY_OPERATORS
    479:         sql << PAREN_OPEN
    480:         c = false
    481:         op_str = " #{op} "
    482:         args.each do |a|
    483:           sql << op_str if c
    484:           literal_append(sql, a)
    485:           c ||= true
    486:         end
    487:         sql << PAREN_CLOSE
    488:       when :NOT
    489:         sql << NOT_SPACE
    490:         literal_append(sql, args.at(0))
    491:       when :NOOP
    492:         literal_append(sql, args.at(0))
    493:       when 'B~''B~'
    494:         sql << TILDE
    495:         literal_append(sql, args.at(0))
    496:       when :extract
    497:         sql << EXTRACT << args.at(0).to_s << FROM
    498:         literal_append(sql, args.at(1))
    499:         sql << PAREN_CLOSE
    500:       else
    501:         raise(InvalidOperation, "invalid operator #{op}")
    502:       end
    503:     end

constant_sql_append(sql, constant)

SQL fragment for constants

[Source]

         # File lib/sequel/dataset/sql.rb, line 506
    506:     def constant_sql_append(sql, constant)
    507:       sql << constant.to_s
    508:     end

function_sql_append(sql, f)

SQL fragment specifying an SQL function call

[Source]

         # File lib/sequel/dataset/sql.rb, line 511
    511:     def function_sql_append(sql, f)
    512:       sql << f.f.to_s
    513:       args = f.args
    514:       if args.empty?
    515:         sql << FUNCTION_EMPTY
    516:       else
    517:         literal_append(sql, args)
    518:       end
    519:     end

join_clause_sql_append(sql, jc)

SQL fragment specifying a JOIN clause without ON or USING.

[Source]

         # File lib/sequel/dataset/sql.rb, line 522
    522:     def join_clause_sql_append(sql, jc)
    523:       table = jc.table
    524:       table_alias = jc.table_alias
    525:       table_alias = nil if table == table_alias
    526:       sql << SPACE << join_type_sql(jc.join_type) << SPACE
    527:       table_ref_append(sql, table)
    528:       as_sql_append(sql, table_alias) if table_alias
    529:     end

join_on_clause_sql_append(sql, jc)

SQL fragment specifying a JOIN clause with ON.

[Source]

         # File lib/sequel/dataset/sql.rb, line 532
    532:     def join_on_clause_sql_append(sql, jc)
    533:       join_clause_sql_append(sql, jc)
    534:       sql << ON
    535:       literal_append(sql, filter_expr(jc.on))
    536:     end

join_using_clause_sql_append(sql, jc)

SQL fragment specifying a JOIN clause with USING.

[Source]

         # File lib/sequel/dataset/sql.rb, line 539
    539:     def join_using_clause_sql_append(sql, jc)
    540:       join_clause_sql_append(sql, jc)
    541:       sql << USING
    542:       column_list_append(sql, jc.using)
    543:       sql << PAREN_CLOSE
    544:     end

negative_boolean_constant_sql_append(sql, constant)

SQL fragment for NegativeBooleanConstants

[Source]

         # File lib/sequel/dataset/sql.rb, line 547
    547:     def negative_boolean_constant_sql_append(sql, constant)
    548:       sql << NOT_SPACE
    549:       boolean_constant_sql_append(sql, constant)
    550:     end

ordered_expression_sql_append(sql, oe)

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 554
    554:     def ordered_expression_sql_append(sql, oe)
    555:       literal_append(sql, oe.expression)
    556:       sql << (oe.descending ? DESC : ASC)
    557:       case oe.nulls
    558:       when :first
    559:         sql << NULLS_FIRST
    560:       when :last
    561:         sql << NULLS_LAST
    562:       end
    563:     end

placeholder_literal_string_sql_append(sql, pls)

SQL fragment for a literal string with placeholders

[Source]

         # File lib/sequel/dataset/sql.rb, line 566
    566:     def placeholder_literal_string_sql_append(sql, pls)
    567:       args = pls.args
    568:       sql << PAREN_OPEN if pls.parens
    569:       if args.is_a?(Hash)
    570:         re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
    571:         if RUBY_VERSION >= '1.8.7'
    572:           str = pls.str
    573:           loop do
    574:             previous, q, str = str.partition(re)
    575:             sql << previous
    576:             literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
    577:             break if str.empty?
    578:           end
    579:         else
    580:           sql << pls.str.gsub(re){literal(args[$1.to_sym])}
    581:         end
    582:       else
    583:         i = -1
    584:         if RUBY_VERSION >= '1.8.7'
    585:           str = pls.str
    586:           loop do
    587:             previous, q, str = str.partition(QUESTION_MARK)
    588:             sql << previous
    589:             literal_append(sql, args.at(i+=1)) unless q.empty?
    590:             break if str.empty?
    591:           end
    592:         else
    593:           sql << pls.str.gsub(QUESTION_MARK_RE){literal(args.at(i+=1))}
    594:         end
    595:       end
    596:       sql << PAREN_CLOSE if pls.parens
    597:     end

qualified_identifier_sql_append(sql, qcr)

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 601
    601:     def qualified_identifier_sql_append(sql, qcr)
    602:       case t = qcr.table
    603:       when Symbol, SQL::QualifiedIdentifier, SQL::Identifier
    604:         literal_append(sql, t)
    605:       else
    606:         quote_identifier_append(sql, t)
    607:       end
    608:       sql << DOT
    609:       case c = qcr.column
    610:       when Symbol, SQL::QualifiedIdentifier, SQL::Identifier
    611:         literal_append(sql, c)
    612:       else
    613:         quote_identifier_append(sql, c)
    614:       end
    615:     end

quote_identifier_append(sql, name)

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 620
    620:     def quote_identifier_append(sql, name)
    621:       if name.is_a?(LiteralString)
    622:         sql << name
    623:       else
    624:         name = name.value if name.is_a?(SQL::Identifier)
    625:         name = input_identifier(name)
    626:         if quote_identifiers?
    627:           quoted_identifier_append(sql, name)
    628:         else
    629:           sql << name
    630:         end
    631:       end
    632:     end

quote_schema_table_append(sql, table)

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 636
    636:     def quote_schema_table_append(sql, table)
    637:       schema, table = schema_and_table(table)
    638:       if schema
    639:         quote_identifier_append(sql, schema)
    640:         sql << DOT
    641:       end
    642:       quote_identifier_append(sql, table)
    643:     end

quoted_identifier_append(sql, name)

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 648
    648:     def quoted_identifier_append(sql, name)
    649:       sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE
    650:     end

schema_and_table(table_name)

Split the schema information from the table

[Source]

         # File lib/sequel/dataset/sql.rb, line 653
    653:     def schema_and_table(table_name)
    654:       sch = db.default_schema if db
    655:       case table_name
    656:       when Symbol
    657:         s, t, a = split_symbol(table_name)
    658:         [s||sch, t]
    659:       when SQL::QualifiedIdentifier
    660:         [table_name.table, table_name.column]
    661:       when SQL::Identifier
    662:         [sch, table_name.value]
    663:       when String
    664:         [sch, table_name]
    665:       else
    666:         raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
    667:       end
    668:     end

subscript_sql_append(sql, s)

SQL fragment for specifying subscripts (SQL array accesses)

[Source]

         # File lib/sequel/dataset/sql.rb, line 671
    671:     def subscript_sql_append(sql, s)
    672:       literal_append(sql, s.f)
    673:       sql << BRACKET_OPEN
    674:       expression_list_append(sql, s.sub)
    675:       sql << BRACKET_CLOSE
    676:     end

window_function_sql_append(sql, function, window)

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 720
    720:     def window_function_sql_append(sql, function, window)
    721:       literal_append(sql, function)
    722:       sql << OVER
    723:       literal_append(sql, window)
    724:     end

window_sql_append(sql, opts)

The SQL fragment for the given window‘s options.

[Source]

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

### Protected Instance methods

_insert_sql()

Formats in INSERT statement using the stored columns and values.

[Source]

         # File lib/sequel/dataset/sql.rb, line 729
    729:     def _insert_sql
    730:       clause_sql(:insert)
    731:     end

_update_sql()

Formats an UPDATE statement using the stored values.

[Source]

         # File lib/sequel/dataset/sql.rb, line 734
    734:     def _update_sql
    735:       clause_sql(:update)
    736:     end

compound_from_self()

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

[Source]

         # File lib/sequel/dataset/sql.rb, line 740
    740:     def compound_from_self
    741:       (@opts[:limit] || @opts[:order]) ? from_self : self
    742:     end

## 7 - Mutation methods

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

### Classes and Modules

Module Sequel::Dataset::Pagination
Module Sequel::Dataset::QueryBlockCopy

### Constants

MUTATION_METHODS | = | QUERY_METHODS |  | 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

def_mutation_method(*meths)

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.

[Source]

        # File lib/sequel/dataset/mutation.rb, line 14
    14:     def self.def_mutation_method(*meths)
    15:       meths.each do |meth|
    16:         class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__)
    17:       end
    18:     end

introspect_all_columns()

Enable column introspection for every dataset.

[Source]

        # File lib/sequel/extensions/columns_introspection.rb, line 56
    56:     def self.introspect_all_columns
    57:       include ColumnsIntrospection
    58:       remove_method(:columns) if instance_methods(false).map{|x| x.to_s}.include?('columns')
    59:     end

### Public Instance methods

columns_without_introspection()

Alias for columns

def_mutation_method(*meths)

Add a mutation method to this dataset instance.

[Source]

        # File lib/sequel/dataset/mutation.rb, line 37
    37:     def def_mutation_method(*meths)
    38:       meths.each do |meth|
    39:         instance_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__)
    40:       end
    41:     end

each_page(page_size) {|paginate(page_no, page_size, record_count)}| ...}

Yields a paginated dataset for each page and returns the receiver. Does a count to find the total number of records for this dataset.

[Source]

        # File lib/sequel/extensions/pagination.rb, line 20
    20:     def each_page(page_size)
    21:       raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit]
    22:       record_count = count
    23:       total_pages = (record_count / page_size.to_f).ceil
    24:       (1..total_pages).each{|page_no| yield paginate(page_no, page_size, record_count)}
    25:       self
    26:     end

paginate(page_no, page_size, record_count=nil)

Returns a paginated dataset. The returned dataset is limited to the page size at the correct offset, and extended with the Pagination module. If a record count is not provided, does a count of total number of records for this dataset.

[Source]

        # File lib/sequel/extensions/pagination.rb, line 11
    11:     def paginate(page_no, page_size, record_count=nil)
    12:       raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit]
    13:       paginated = limit(page_size, (page_no - 1) * page_size)
    14:       paginated.extend(Pagination)
    15:       paginated.set_pagination_info(page_no, page_size, record_count || count)
    16:     end

print(*cols)

Pretty prints the records in the dataset as plain-text table.

[Source]

        # File lib/sequel/extensions/pretty_table.rb, line 8
     8:     def print(*cols)
     9:       Sequel::PrettyTable.print(naked.all, cols.empty? ? columns : cols)
    10:     end

query(&block)

Translates a query block into a dataset. Query blocks can be useful when expressing complex SELECT statements, e.g.:

      dataset = DB[:items].query do
        select :x, :y, :z
        filter{|o| (o.x > 1) & (o.y > 2)}
        order :z.desc
      end

Which is the same as:

     dataset = DB[:items].select(:x, :y, :z).filter{|o| (o.x > 1) & (o.y > 2)}.order(:z.desc)

Note that inside a call to query, you cannot call each, insert, update, or delete (or any method that calls those), or Sequel will raise an error.

[Source]

        # File lib/sequel/extensions/query.rb, line 30
    30:     def query(&block)
    31:       copy = clone({})
    32:       copy.extend(QueryBlockCopy)
    33:       copy.instance_eval(&block)
    34:       clone(copy.opts)
    35:     end

to_dot()

Return a string that can be processed by the `dot` program (included with graphviz) in order to see a visualization of the dataset‘s abstract syntax tree.

[Source]

         # File lib/sequel/extensions/to_dot.rb, line 145
    145:     def to_dot
    146:       ToDot.output(self)
    147:     end

[Validate]