### Home Classes Methods

### In Files

- lib/sequel/dataset/sql.rb
- lib/sequel/dataset/prepared_statements.rb
- lib/sequel/dataset/features.rb
- lib/sequel/dataset/actions.rb
- lib/sequel/dataset/mutation.rb
- lib/sequel/dataset/graph.rb
- lib/sequel/dataset/query.rb
- lib/sequel/dataset/misc.rb
- lib/sequel/dataset.rb
- lib/sequel/extensions/pagination.rb
- lib/sequel/extensions/pretty_table.rb
- lib/sequel/extensions/query.rb
- lib/sequel/adapters/utils/stored_procedures.rb

### Parent

Object

### Sections

- Internal Methods relating to SQL Creation
- Methods related to dataset graphing
- Methods related to prepared statements or bound variables
- Methods that describe what the dataset supports
- Methods that execute code on the database
- Methods that return modified datasets
- Miscellaneous methods
- Mutation methods
- User Methods relating to SQL Creation

### Namespace

- MODULE Sequel::Dataset::ArgumentMapper
- MODULE Sequel::Dataset::Pagination
- MODULE Sequel::Dataset::PreparedStatementMethods
- MODULE Sequel::Dataset::QueryBlockCopy
- MODULE Sequel::Dataset::StoredProcedureMethods
- MODULE Sequel::Dataset::StoredProcedures
- MODULE Sequel::Dataset::UnnumberedArgumentMapper

### Methods

- ::clause_methods
- ::def_mutation_method
- ::new
- #<<
- #[]
- #[]=
- #_insert_sql
- #_update_sql
- #add_graph_aliases
- #aliased_expression_sql
- #all
- #and
- #array_sql
- #as
- #avg
- #bind
- #boolean_constant_sql
- #call
- #case_expression_sql
- #cast_sql
- #clone
- #column_all_sql
- #columns
- #columns!
- #complex_expression_sql
- #compound_from_self
- #constant_sql
- #count
- #def_mutation_method
- #delete
- #delete_sql
- #distinct
- #each
- #each_page
- #each_server
- #empty?
- #except
- #exclude
- #exists
- #fetch_rows
- #filter
- #first
- #first_source
- #first_source_alias
- #first_source_table
- #for_update
- #from
- #from_self
- #function_sql
- #get
- #graph
- #grep
- #group
- #group_and_count
- #group_by
- #having
- #import
- #insert
- #insert_multiple
- #insert_sql
- #inspect
- #intersect
- #interval
- #invert
- #join
- #join_clause_sql
- #join_on_clause_sql
- #join_table
- #join_using_clause_sql
- #last
- #limit
- #literal
- #lock_style
- #map
- #max
- #min
- #multi_insert
- #multi_insert_sql
- #naked
- #negative_boolean_constant_sql
- #options_overlap
- #or
- #order
- #order_append
- #order_by
- #order_more
- #order_prepend
- #ordered_expression_sql
- #paginate
- #placeholder_literal_string_sql
- #prepare
- #print
- #provides_accurate_rows_matched?
- #qualified_identifier_sql
- #qualify
- #qualify_to
- #qualify_to_first_source
- #query
- #quote_identifier
- #quote_identifiers?
- #quote_schema_table
- #quoted_identifier
- #range
- #requires_sql_standard_datetimes?
- #reverse
- #reverse_order
- #schema_and_table
- #select
- #select_all
- #select_append
- #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
- #sql
- #subscript_sql
- #sum
- #supports_cte?
- #supports_distinct_on?
- #supports_intersect_except?
- #supports_intersect_except_all?
- #supports_is_true?
- #supports_join_using?
- #supports_modifying_joins?
- #supports_multiple_column_in?
- #supports_timestamp_timezones?
- #supports_timestamp_usecs?
- #supports_window_functions?
- #to_csv
- #to_hash
- #to_prepared_statement
- #truncate
- #truncate_sql
- #unfiltered
- #ungraphed
- #ungrouped
- #union
- #unlimited
- #unordered
- #unused_table_alias
- #update
- #update_sql
- #where
- #window_function_sql
- #window_sql
- #with
- #with_recursive
- #with_sql

### Included Modules

- Sequel::Metaprogramming
- Enumerable

### Files

- CHANGELOG
- COPYING
- README.rdoc
- advanced_associations.rdoc
- association_basics.rdoc
- cheat_sheet.rdoc
- dataset_basics.rdoc
- dataset_filtering.rdoc
- migration.rdoc
- model_hooks.rdoc
- opening_databases.rdoc
- prepared_statements.rdoc
- querying.rdoc
- reflection.rdoc
- 1.0.txt
- 1.1.txt
- 1.3.txt
- 1.4.0.txt
- 1.5.0.txt
- 2.0.0.txt
- 2.1.0.txt
- 2.10.0.txt
- 2.11.0.txt
- 2.12.0.txt
- 2.2.0.txt
- 2.3.0.txt
- 2.4.0.txt
- 2.5.0.txt
- 2.6.0.txt
- 2.7.0.txt
- 2.8.0.txt
- 2.9.0.txt
- 3.0.0.txt
- 3.1.0.txt
- 3.10.0.txt
- 3.11.0.txt
- 3.12.0.txt
- 3.2.0.txt
- 3.3.0.txt
- 3.4.0.txt
- 3.5.0.txt
- 3.6.0.txt
- 3.7.0.txt
- 3.8.0.txt
- 3.9.0.txt
- sharding.rdoc
- sql.rdoc
- virtual_rows.rdoc

### Class/Module Index

Quicksearch

- Sequel
- Sequel::ADO
- Sequel::ADO::Database
- Sequel::ADO::Dataset
- Sequel::ADO::MSSQL
- Sequel::ADO::MSSQL::DatabaseMethods
- Sequel::ADO::MSSQL::Dataset
- Sequel::AdapterNotFound
- Sequel::Amalgalite
- Sequel::Amalgalite::Database
- Sequel::Amalgalite::Dataset
- Sequel::Amalgalite::SequelTypeMap
- Sequel::BasicObject
- Sequel::BeforeHookFailed
- Sequel::ConnectionPool
- Sequel::ConnectionPool::ClassMethods
- Sequel::DB2
- Sequel::DB2::Database
- Sequel::DB2::Dataset
- Sequel::DBI
- Sequel::DBI::Database
- Sequel::DBI::Dataset
- Sequel::DataObjects
- Sequel::DataObjects::Database
- Sequel::DataObjects::Dataset
- Sequel::DataObjects::MySQL
- Sequel::DataObjects::MySQL::DatabaseMethods
- Sequel::DataObjects::MySQL::Dataset
- Sequel::DataObjects::Postgres
- Sequel::DataObjects::Postgres::AdapterMethods
- Sequel::DataObjects::Postgres::DatabaseMethods
- Sequel::DataObjects::Postgres::Dataset
- Sequel::DataObjects::SQLite
- Sequel::DataObjects::SQLite::DatabaseMethods
- Sequel::DataObjects::SQLite::Dataset
- Sequel::Database
- Sequel::DatabaseConnectionError
- Sequel::DatabaseDisconnectError
- Sequel::DatabaseError
- Sequel::Dataset
- Sequel::Dataset::ArgumentMapper
- Sequel::Dataset::Pagination
- Sequel::Dataset::PreparedStatementMethods
- Sequel::Dataset::QueryBlockCopy
- Sequel::Dataset::StoredProcedureMethods
- Sequel::Dataset::StoredProcedures
- Sequel::Dataset::UnnumberedArgumentMapper
- Sequel::Error
- Sequel::Error::AdapterNotFound
- Sequel::Error::InvalidOperation
- Sequel::Error::InvalidValue
- Sequel::Error::PoolTimeoutError
- Sequel::Error::Rollback
- Sequel::Firebird
- Sequel::Firebird::Database
- Sequel::Firebird::Dataset
- Sequel::Inflections
- Sequel::Informix
- Sequel::Informix::Database
- Sequel::Informix::Dataset
- Sequel::IntegerMigrator
- Sequel::InvalidOperation
- Sequel::InvalidValue
- Sequel::JDBC
- Sequel::JDBC::AS400
- Sequel::JDBC::AS400::DatabaseMethods
- Sequel::JDBC::AS400::Dataset
- Sequel::JDBC::Database
- Sequel::JDBC::Dataset
- Sequel::JDBC::Dataset::PreparedStatementMethods
- Sequel::JDBC::Dataset::StoredProcedureMethods
- Sequel::JDBC::H2
- Sequel::JDBC::H2::DatabaseMethods
- Sequel::JDBC::H2::Dataset
- Sequel::JDBC::JavaLang
- Sequel::JDBC::JavaSQL
- Sequel::JDBC::JavaxNaming
- Sequel::JDBC::MSSQL
- Sequel::JDBC::MSSQL::DatabaseMethods
- Sequel::JDBC::MSSQL::Dataset
- Sequel::JDBC::MySQL
- Sequel::JDBC::MySQL::DatabaseMethods
- Sequel::JDBC::MySQL::Dataset
- Sequel::JDBC::Oracle
- Sequel::JDBC::Oracle::DatabaseMethods
- Sequel::JDBC::Oracle::Dataset
- Sequel::JDBC::Postgres
- Sequel::JDBC::Postgres::AdapterMethods
- Sequel::JDBC::Postgres::DatabaseMethods
- Sequel::JDBC::Postgres::Dataset
- Sequel::JDBC::SQLite
- Sequel::JDBC::SQLite::DatabaseMethods
- Sequel::JDBC::SQLite::Dataset
- Sequel::LiteralString
- Sequel::LooserTypecasting
- Sequel::MSSQL
- Sequel::MSSQL::DatabaseMethods
- Sequel::MSSQL::DatasetMethods
- Sequel::Metaprogramming
- Sequel::Migration
- Sequel::MigrationDSL
- Sequel::Migrator
- Sequel::Migrator::Error
- Sequel::Model
- Sequel::Model::Associations
- Sequel::Model::Associations::AssociationDatasetMethods
- Sequel::Model::Associations::AssociationReflection
- Sequel::Model::Associations::ClassMethods
- Sequel::Model::Associations::DatasetMethods
- Sequel::Model::Associations::InstanceMethods
- Sequel::Model::Associations::ManyToManyAssociationReflection
- Sequel::Model::Associations::ManyToOneAssociationReflection
- Sequel::Model::Associations::OneToManyAssociationReflection
- Sequel::Model::Associations::OneToOneAssociationReflection
- Sequel::Model::ClassMethods
- Sequel::Model::DatasetMethods
- Sequel::Model::Errors
- Sequel::Model::InstanceMethods
- Sequel::MySQL
- Sequel::MySQL::Database
- Sequel::MySQL::DatabaseMethods
- Sequel::MySQL::Dataset
- Sequel::MySQL::Dataset::CallableStatementMethods
- Sequel::MySQL::Dataset::PreparedStatementMethods
- Sequel::MySQL::Dataset::StoredProcedureMethods
- Sequel::MySQL::DatasetMethods
- Sequel::NamedTimezones
- Sequel::NoExistingObject
- Sequel::NotImplemented
- Sequel::ODBC
- Sequel::ODBC::Database
- Sequel::ODBC::Dataset
- Sequel::ODBC::MSSQL
- Sequel::ODBC::MSSQL::DatabaseMethods
- Sequel::ODBC::MSSQL::Dataset
- Sequel::OpenBase
- Sequel::OpenBase::Database
- Sequel::OpenBase::Dataset
- Sequel::Oracle
- Sequel::Oracle::Database
- Sequel::Oracle::DatabaseMethods
- Sequel::Oracle::Dataset
- Sequel::Oracle::DatasetMethods
- Sequel::Plugins
- Sequel::Plugins::ActiveModel
- Sequel::Plugins::ActiveModel::InstanceMethods
- Sequel::Plugins::AssociationDependencies
- Sequel::Plugins::AssociationDependencies::ClassMethods
- Sequel::Plugins::AssociationDependencies::InstanceMethods
- Sequel::Plugins::AssociationPks
- Sequel::Plugins::AssociationPks::ClassMethods
- Sequel::Plugins::AssociationProxies
- Sequel::Plugins::AssociationProxies::AssociationProxy
- Sequel::Plugins::AssociationProxies::ClassMethods
- Sequel::Plugins::BooleanReaders
- Sequel::Plugins::BooleanReaders::ClassMethods
- Sequel::Plugins::Caching
- Sequel::Plugins::Caching::ClassMethods
- Sequel::Plugins::Caching::InstanceMethods
- Sequel::Plugins::ClassTableInheritance
- Sequel::Plugins::ClassTableInheritance::ClassMethods
- Sequel::Plugins::ClassTableInheritance::InstanceMethods
- Sequel::Plugins::Composition
- Sequel::Plugins::Composition::ClassMethods
- Sequel::Plugins::Composition::InstanceMethods
- Sequel::Plugins::ForceEncoding
- Sequel::Plugins::ForceEncoding::ClassMethods
- Sequel::Plugins::ForceEncoding::InstanceMethods
- Sequel::Plugins::HookClassMethods
- Sequel::Plugins::HookClassMethods::ClassMethods
- Sequel::Plugins::HookClassMethods::InstanceMethods
- Sequel::Plugins::IdentityMap
- Sequel::Plugins::IdentityMap::ClassMethods
- Sequel::Plugins::IdentityMap::InstanceMethods
- Sequel::Plugins::InstanceFilters
- Sequel::Plugins::InstanceFilters::InstanceMethods
- Sequel::Plugins::InstanceHooks
- Sequel::Plugins::InstanceHooks::InstanceMethods
- Sequel::Plugins::LazyAttributes
- Sequel::Plugins::LazyAttributes::ClassMethods
- Sequel::Plugins::LazyAttributes::InstanceMethods
- Sequel::Plugins::ManyThroughMany
- Sequel::Plugins::ManyThroughMany::ClassMethods
- Sequel::Plugins::ManyThroughMany::ManyThroughManyAssociationReflection
- Sequel::Plugins::NestedAttributes
- Sequel::Plugins::NestedAttributes::ClassMethods
- Sequel::Plugins::NestedAttributes::InstanceMethods
- Sequel::Plugins::OptimisticLocking
- Sequel::Plugins::OptimisticLocking::ClassMethods
- Sequel::Plugins::OptimisticLocking::InstanceMethods
- Sequel::Plugins::RcteTree
- Sequel::Plugins::Schema
- Sequel::Plugins::Schema::ClassMethods
- Sequel::Plugins::Serialization
- Sequel::Plugins::Serialization::ClassMethods
- Sequel::Plugins::Serialization::InstanceMethods
- Sequel::Plugins::Sharding
- Sequel::Plugins::Sharding::ClassMethods
- Sequel::Plugins::Sharding::DatasetMethods
- Sequel::Plugins::Sharding::InstanceMethods
- Sequel::Plugins::SingleTableInheritance
- Sequel::Plugins::SingleTableInheritance::ClassMethods
- Sequel::Plugins::SingleTableInheritance::InstanceMethods
- Sequel::Plugins::SkipCreateRefresh
- Sequel::Plugins::SkipCreateRefresh::InstanceMethods
- Sequel::Plugins::StringStripper
- Sequel::Plugins::StringStripper::InstanceMethods
- Sequel::Plugins::Subclasses
- Sequel::Plugins::Subclasses::ClassMethods
- Sequel::Plugins::TacticalEagerLoading
- Sequel::Plugins::TacticalEagerLoading::DatasetMethods
- Sequel::Plugins::TacticalEagerLoading::InstanceMethods
- Sequel::Plugins::Timestamps
- Sequel::Plugins::Timestamps::ClassMethods
- Sequel::Plugins::Timestamps::InstanceMethods
- Sequel::Plugins::Touch
- Sequel::Plugins::Touch::ClassMethods
- Sequel::Plugins::Touch::InstanceMethods
- Sequel::Plugins::TypecastOnLoad
- Sequel::Plugins::TypecastOnLoad::ClassMethods
- Sequel::Plugins::TypecastOnLoad::InstanceMethods
- Sequel::Plugins::UpdatePrimaryKey
- Sequel::Plugins::UpdatePrimaryKey::ClassMethods
- Sequel::Plugins::UpdatePrimaryKey::InstanceMethods
- Sequel::Plugins::ValidationClassMethods
- Sequel::Plugins::ValidationClassMethods::ClassMethods
- Sequel::Plugins::ValidationClassMethods::ClassMethods::Generator
- Sequel::Plugins::ValidationClassMethods::InstanceMethods
- Sequel::Plugins::ValidationHelpers
- Sequel::Plugins::ValidationHelpers::InstanceMethods
- Sequel::PoolTimeout
- Sequel::Postgres
- Sequel::Postgres::Adapter
- Sequel::Postgres::AdapterMethods
- Sequel::Postgres::Database
- Sequel::Postgres::DatabaseMethods
- Sequel::Postgres::Dataset
- Sequel::Postgres::Dataset::ArgumentMapper
- Sequel::Postgres::Dataset::BindArgumentMethods
- Sequel::Postgres::Dataset::PreparedStatementMethods
- Sequel::Postgres::DatasetMethods
- Sequel::Postgres::DatasetMethods::PreparedStatementMethods
- Sequel::PrettyTable
- Sequel::Progress
- Sequel::Progress::DatabaseMethods
- Sequel::Progress::DatasetMethods
- Sequel::Rollback
- Sequel::SQL
- Sequel::SQL::AliasMethods
- Sequel::SQL::AliasedExpression
- Sequel::SQL::BitwiseMethods
- Sequel::SQL::Blob
- Sequel::SQL::BooleanConstant
- Sequel::SQL::BooleanExpression
- Sequel::SQL::BooleanMethods
- Sequel::SQL::CaseExpression
- Sequel::SQL::Cast
- Sequel::SQL::CastMethods
- Sequel::SQL::ColumnAll
- Sequel::SQL::ComplexExpression
- Sequel::SQL::ComplexExpressionMethods
- Sequel::SQL::Constant
- Sequel::SQL::Constants
- Sequel::SQL::Expression
- Sequel::SQL::Function
- Sequel::SQL::GenericComplexExpression
- Sequel::SQL::GenericExpression
- Sequel::SQL::Identifier
- Sequel::SQL::IdentifierMethods
- Sequel::SQL::InequalityMethods
- Sequel::SQL::JoinClause
- Sequel::SQL::JoinOnClause
- Sequel::SQL::JoinUsingClause
- Sequel::SQL::NegativeBooleanConstant
- Sequel::SQL::NoBooleanInputMethods
- Sequel::SQL::NumericExpression
- Sequel::SQL::NumericMethods
- Sequel::SQL::OrderMethods
- Sequel::SQL::OrderedExpression
- Sequel::SQL::PlaceholderLiteralString
- Sequel::SQL::QualifiedIdentifier
- Sequel::SQL::QualifyingMethods
- Sequel::SQL::SQLArray
- Sequel::SQL::StringConcatenationMethods
- Sequel::SQL::StringExpression
- Sequel::SQL::StringMethods
- Sequel::SQL::Subscript
- Sequel::SQL::SubscriptMethods
- Sequel::SQL::VirtualRow
- Sequel::SQL::Window
- Sequel::SQL::WindowFunction
- Sequel::SQLite
- Sequel::SQLite::Database
- Sequel::SQLite::DatabaseMethods
- Sequel::SQLite::Dataset
- Sequel::SQLite::Dataset::ArgumentMapper
- Sequel::SQLite::Dataset::PreparedStatementMethods
- Sequel::SQLite::DatasetMethods
- Sequel::Schema
- Sequel::Schema::AlterTableGenerator
- Sequel::Schema::Generator
- Sequel::ShardedSingleConnectionPool
- Sequel::ShardedThreadedConnectionPool
- Sequel::SimpleMigration
- Sequel::SingleConnectionPool
- Sequel::ThreadLocalTimezones
- Sequel::ThreadedConnectionPool
- Sequel::TimestampMigrator
- Sequel::Timezones
- Sequel::ValidationFailed
- String
- String::Inflections
- Array
- FalseClass
- Hash
- NilClass
- Numeric
- Object
- PGconn
- PGresult
- Proc
- Symbol
- TrueClass

No matching classes.

# 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.

## Internal Methods relating to SQL Creation ↑ top

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

### Constants

AND_SEPARATOR
BOOL_FALSE
BOOL_TRUE
COLUMN_REF_RE1
COLUMN_REF_RE2
COLUMN_REF_RE3
COMMA_SEPARATOR
COUNT_FROM_SELF_OPTS
COUNT_OF_ALL_AS_COUNT
DATASET_ALIAS_BASE_NAME
DELETE_CLAUSE_METHODS
FOR_UPDATE
INSERT_CLAUSE_METHODS
IS_LITERALS
IS_OPERATORS
NULL
N_ARITY_OPERATORS
QUALIFY_KEYS
QUESTION_MARK
SELECT_CLAUSE_METHODS
SQL_WITH
STANDARD_TIMESTAMP_FORMAT
TIMESTAMP_FORMAT
TWO_ARITY_OPERATORS
UPDATE_CLAUSE_METHODS
WILDCARD

### Public Class Methods

clause_methods(type, clauses) click to toggle source

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

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

### Public Instance Methods

aliased_expression_sql(ae) click to toggle source

SQL fragment for the aliased expression

    # File lib/sequel/dataset/sql.rb, line 214
    def aliased_expression_sql(ae)
      as_sql(literal(ae.expression), ae.aliaz)
    end

array_sql(a) click to toggle source

SQL fragment for the SQL array.

    # File lib/sequel/dataset/sql.rb, line 219
    def array_sql(a)
      a.empty? ? '(NULL)' : "(#{expression_list(a)})"
    end

boolean_constant_sql(constant) click to toggle source

SQL fragment for BooleanConstants

    # File lib/sequel/dataset/sql.rb, line 224
    def boolean_constant_sql(constant)
      literal(constant)
    end

case_expression_sql(ce) click to toggle source

SQL fragment for specifying given CaseExpression.

    # File lib/sequel/dataset/sql.rb, line 229
    def case_expression_sql(ce)
      sql = '(CASE '
      sql << "#{literal(ce.expression)} " if ce.expression
      ce.conditions.collect{ |c,r|
        sql << "WHEN #{literal(c)} THEN #{literal(r)} "
      }
      sql << "ELSE #{literal(ce.default)} END)"
    end

cast_sql(expr, type) click to toggle source

SQL fragment for the SQL CAST expression.

    # File lib/sequel/dataset/sql.rb, line 239
    def cast_sql(expr, type)
      "CAST(#{literal(expr)} AS #{db.cast_type_literal(type)})"
    end

column_all_sql(ca) click to toggle source

SQL fragment for specifying all columns in a given table.

    # File lib/sequel/dataset/sql.rb, line 244
    def column_all_sql(ca)
      "#{quote_schema_table(ca.table)}.*"
    end

complex_expression_sql(op, args) click to toggle source

SQL fragment for complex expressions

    # File lib/sequel/dataset/sql.rb, line 249
    def complex_expression_sql(op, args)
      case op
      when *IS_OPERATORS
        r = args.at(1)
        if r.nil? || supports_is_true?
          raise(InvalidOperation, 'Invalid argument used for IS operator') unless v = IS_LITERALS[r]
          "(#{literal(args.at(0))} #{op} #{v})"
        elsif op == :IS
          complex_expression_sql(:"=", args)
        else
          complex_expression_sql(:OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)])
        end
      when :IN, :"NOT IN"
        cols = args.at(0)
        vals = args.at(1)
        col_array = true if cols.is_a?(Array) || cols.is_a?(SQL::SQLArray)
        if vals.is_a?(Array) || vals.is_a?(SQL::SQLArray)
          val_array = true
          empty_val_array = vals.to_a == []
        end
        if col_array
          if empty_val_array
            if op == :IN
              literal(SQL::BooleanExpression.from_value_pairs(cols.to_a.map{|x| [x, x]}, :AND, true))
            else
              literal(1=>1)
            end
          elsif !supports_multiple_column_in?
            if val_array
              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]})})
              literal(op == :IN ? expr : ~expr)
            else
              old_vals = vals
              vals = vals.to_a
              val_cols = old_vals.columns
              complex_expression_sql(op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
            end
          else
            "(#{literal(cols)} #{op} #{literal(vals)})"
          end
        else
          if empty_val_array
            if op == :IN
              literal(SQL::BooleanExpression.from_value_pairs([[cols, cols]], :AND, true))
            else
              literal(1=>1)
            end
          else
            "(#{literal(cols)} #{op} #{literal(vals)})"
          end
        end
      when *TWO_ARITY_OPERATORS
        "(#{literal(args.at(0))} #{op} #{literal(args.at(1))})"
      when *N_ARITY_OPERATORS
        "(#{args.collect{|a| literal(a)}.join(" #{op} ")})"
      when :NOT
        "NOT #{literal(args.at(0))}"
      when :NOOP
        literal(args.at(0))
      when :'B~'
        "~#{literal(args.at(0))}"
      else
        raise(InvalidOperation, "invalid operator #{op}")
      end
    end

constant_sql(constant) click to toggle source

SQL fragment for constants

    # File lib/sequel/dataset/sql.rb, line 316
    def constant_sql(constant)
      constant.to_s
    end

function_sql(f) click to toggle source

SQL fragment specifying an SQL function call

    # File lib/sequel/dataset/sql.rb, line 321
    def function_sql(f)
      args = f.args
      "#{f.f}#{args.empty? ? '()' : literal(args)}"
    end

join_clause_sql(jc) click to toggle source

SQL fragment specifying a JOIN clause without ON or USING.

    # File lib/sequel/dataset/sql.rb, line 327
    def join_clause_sql(jc)
      table = jc.table
      table_alias = jc.table_alias
      table_alias = nil if table == table_alias
      tref = table_ref(table)
      " #{join_type_sql(jc.join_type)} #{table_alias ? as_sql(tref, table_alias) : tref}"
    end

join_on_clause_sql(jc) click to toggle source

SQL fragment specifying a JOIN clause with ON.

    # File lib/sequel/dataset/sql.rb, line 336
    def join_on_clause_sql(jc)
      "#{join_clause_sql(jc)} ON #{literal(filter_expr(jc.on))}"
    end

join_using_clause_sql(jc) click to toggle source

SQL fragment specifying a JOIN clause with USING.

    # File lib/sequel/dataset/sql.rb, line 341
    def join_using_clause_sql(jc)
      "#{join_clause_sql(jc)} USING (#{column_list(jc.using)})"
    end

negative_boolean_constant_sql(constant) click to toggle source

SQL fragment for NegativeBooleanConstants

    # File lib/sequel/dataset/sql.rb, line 346
    def negative_boolean_constant_sql(constant)
      "NOT #{boolean_constant_sql(constant)}"
    end

ordered_expression_sql(oe) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 352
    def ordered_expression_sql(oe)
      "#{literal(oe.expression)} #{oe.descending ? 'DESC' : 'ASC'}"
    end

placeholder_literal_string_sql(pls) click to toggle source

SQL fragment for a literal string with placeholders

    # File lib/sequel/dataset/sql.rb, line 357
    def placeholder_literal_string_sql(pls)
      args = pls.args
      s = if args.is_a?(Hash)
        re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
        pls.str.gsub(re){literal(args[$1.to_sym])}
      else
        i = -1
        pls.str.gsub(QUESTION_MARK){literal(args.at(i+=1))}
      end
      s = "(#{s})" if pls.parens
      s
    end

qualified_identifier_sql(qcr) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 372
    def qualified_identifier_sql(qcr)
      [qcr.table, qcr.column].map{|x| [SQL::QualifiedIdentifier, SQL::Identifier, Symbol].any?{|c| x.is_a?(c)} ? literal(x) : quote_identifier(x)}.join('.')
    end

quote_identifier(name) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 379
    def quote_identifier(name)
      return name if name.is_a?(LiteralString)
      name = name.value if name.is_a?(SQL::Identifier)
      name = input_identifier(name)
      name = quoted_identifier(name) if quote_identifiers?
      name
    end

quote_schema_table(table) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 389
    def quote_schema_table(table)
      schema, table = schema_and_table(table)
      "#{"#{quote_identifier(schema)}." if schema}#{quote_identifier(table)}"
    end

quoted_identifier(name) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 397
    def quoted_identifier(name)
      "\"#{name.to_s.gsub('"', '""')}\""
    end

schema_and_table(table_name) click to toggle source

Split the schema information from the table

    # File lib/sequel/dataset/sql.rb, line 402
    def schema_and_table(table_name)
      sch = db.default_schema if db
      case table_name
      when Symbol
        s, t, a = split_symbol(table_name)
        [s||sch, t]
      when SQL::QualifiedIdentifier
        [table_name.table, table_name.column]
      when SQL::Identifier
        [sch, table_name.value]
      when String
        [sch, table_name]
      else
        raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
      end
    end

subscript_sql(s) click to toggle source

SQL fragment for specifying subscripts (SQL arrays)

    # File lib/sequel/dataset/sql.rb, line 420
    def subscript_sql(s)
      "#{literal(s.f)}[#{expression_list(s.sub)}]"
    end

window_function_sql(function, window) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 444
    def window_function_sql(function, window)
      "#{literal(function)} OVER #{literal(window)}"
    end

window_sql(opts) click to toggle source

The SQL fragment for the given window’s options.

    # File lib/sequel/dataset/sql.rb, line 425
    def window_sql(opts)
      raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
      window = literal(opts[:window]) if opts[:window]
      partition = "PARTITION BY #{expression_list(Array(opts[:partition]))}" if opts[:partition]
      order = "ORDER BY #{expression_list(Array(opts[:order]))}" if opts[:order]
      frame = case opts[:frame]
        when nil
          nil
        when :all
          "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING"
        when :rows
          "ROWS UNBOUNDED PRECEDING"
        else
          raise Error, "invalid window frame clause, should be :all, :rows, or nil"
      end
      "(#{[window, partition, order, frame].compact.join(' ')})"
    end

### Protected Instance Methods

_insert_sql() click to toggle source

Formats in INSERT statement using the stored columns and values.

    # File lib/sequel/dataset/sql.rb, line 451
    def _insert_sql
      clause_sql(:insert)
    end

_update_sql() click to toggle source

Formats an UPDATE statement using the stored values.

    # File lib/sequel/dataset/sql.rb, line 456
    def _update_sql
      clause_sql(:update)
    end

compound_from_self() click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 462
    def compound_from_self
      (@opts[:limit] || @opts[:order]) ? from_self : self
    end

## Methods related to dataset graphing ↑ top

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

### Public Instance Methods

add_graph_aliases(graph_aliases) click to toggle source

Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list. See set_graph_aliases.

    # File lib/sequel/dataset/graph.rb, line 13
    def add_graph_aliases(graph_aliases)
      ds = select_more(*graph_alias_columns(graph_aliases))
      ds.opts[:graph_aliases] = (ds.opts[:graph_aliases] || (ds.opts[:graph][:column_aliases] rescue {}) || {}).merge(graph_aliases)
      ds
    end

graph(dataset, join_conditions = nil, options = {}, &block) click to toggle source

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 return a symbol or a dataset

- join_conditions - Any condition(s) allowed by join_table.

- options - A hash of graph options. The following options are currently used:

  - :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 join that makes it important to use graph instead of join.

  - :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.

- block - A block that is passed to join_table.

    # File lib/sequel/dataset/graph.rb, line 67
    def graph(dataset, join_conditions = nil, options = {}, &block)
      # Allow the use of a model, dataset, or symbol as the first argument
      # Find the table name/dataset based on the argument
      dataset = dataset.dataset if dataset.respond_to?(:dataset)
      table_alias = options[:table_alias]
      case dataset
      when Symbol
        table = dataset
        dataset = @db[dataset]
        table_alias ||= table
      when ::Sequel::Dataset
        if dataset.simple_select_all?
          table = dataset.opts[:from].first
          table_alias ||= table
        else
          table = dataset
          table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
        end
      else
        raise Error, "The dataset argument should be a symbol, dataset, or model"
      end

      # Raise Sequel::Error with explanation that the table alias has been used
      raise_alias_error = lambda do
        raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify "            "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}")
      end

      # Only allow table aliases that haven't been used
      raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)

      # Use a from_self if this is already a joined table
      ds = (!@opts[:graph] && (@opts[:from].length > 1 || @opts[:join])) ? from_self(:alias=>options[:from_self_alias] || first_source) : self

      # Join the table early in order to avoid cloning the dataset twice
      ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>options[:implicit_qualifier], &block)
      opts = ds.opts

      # Whether to include the table in the result set
      add_table = options[:select] == false ? false : true
      # Whether to add the columns to the list of column aliases
      add_columns = !ds.opts.include?(:graph_aliases)

      # Setup the initial graph data structure if it doesn't exist
      unless graph = opts[:graph]
        master = alias_symbol(ds.first_source_alias)
        raise_alias_error.call if master == table_alias
        # Master hash storing all .graph related information
        graph = opts[:graph] = {}
        # Associates column aliases back to tables and columns
        column_aliases = graph[:column_aliases] = {}
        # Associates table alias (the master is never aliased)
        table_aliases = graph[:table_aliases] = {master=>self}
        # Keep track of the alias numbers used
        ca_num = graph[:column_alias_num] = Hash.new(0)
        # All columns in the master table are never
        # aliased, but are not included if set_graph_aliases
        # has been used.
        if add_columns
          select = opts[:select] = []
          columns.each do |column|
            column_aliases[column] = [master, column]
            select.push(SQL::QualifiedIdentifier.new(master, column))
          end
        end
      end

      # Add the table alias to the list of aliases
      # Even if it isn't been used in the result set,
      # we add a key for it with a nil value so we can check if it
      # is used more than once
      table_aliases = graph[:table_aliases]
      table_aliases[table_alias] = add_table ? dataset : nil

      # Add the columns to the selection unless we are ignoring them
      if add_table && add_columns
        select = opts[:select]
        column_aliases = graph[:column_aliases]
        ca_num = graph[:column_alias_num]
        # Which columns to add to the result set
        cols = options[:select] || dataset.columns
        # If the column hasn't been used yet, don't alias it.
        # If it has been used, try table_column.
        # If that has been used, try table_column_N
        # using the next value of N that we know hasn't been
        # used
        cols.each do |column|
          col_alias, identifier = if column_aliases[column]
            column_alias = :"#{table_alias}_#{column}"
            if column_aliases[column_alias]
              column_alias_num = ca_num[column_alias]
              column_alias = :"#{column_alias}_#{column_alias_num}"
              ca_num[column_alias] += 1
            end
            [column_alias, SQL::QualifiedIdentifier.new(table_alias, column).as(column_alias)]
          else
            [column, SQL::QualifiedIdentifier.new(table_alias, column)]
          end
          column_aliases[col_alias] = [table_alias, column]
          select.push(identifier)
        end
      end
      ds
    end

set_graph_aliases(graph_aliases) click to toggle source

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

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

Arguments:

- graph_aliases - Should be a hash with keys being symbols of column aliases, and values being arrays with two or three elements. The first element of the array should be the table alias symbol, and the second should be the actual column name symbol. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.

    # File lib/sequel/dataset/graph.rb, line 189
    def set_graph_aliases(graph_aliases)
      ds = select(*graph_alias_columns(graph_aliases))
      ds.opts[:graph_aliases] = graph_aliases
      ds
    end

ungraphed() click to toggle source

Remove the splitting of results into subhashes. Also removes metadata related to graphing, so you should not call graph any tables to this dataset after calling this method.

    # File lib/sequel/dataset/graph.rb, line 198
    def ungraphed
      clone(:graph=>nil)
    end

## Methods related to prepared statements or bound variables ↑ top

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

### Constants

PREPARED_ARG_PLACEHOLDER

### Public Instance Methods

bind(bind_vars={}) click to toggle source

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

    # File lib/sequel/dataset/prepared_statements.rb, line 179
    def bind(bind_vars={})
      clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars)
    end

call(type, bind_variables={}, *values, &block) click to toggle source

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

    # File lib/sequel/dataset/prepared_statements.rb, line 188
    def call(type, bind_variables={}, *values, &block)
      prepare(type, nil, *values).call(bind_variables, &block)
    end

prepare(type, name=nil, *values) click to toggle source

Prepare an SQL statement for later execution. This returns a clone of the dataset extended with PreparedStatementMethods, on which you can call call with the hash of bind variables to do substitution. The prepared statement is also stored in the associated database. The following usage is identical:

    ps = prepare(:select, :select_by_name)
    ps.call(:name=>'Blah')
    db.call(:select_by_name, :name=>'Blah')

    # File lib/sequel/dataset/prepared_statements.rb, line 201
    def prepare(type, name=nil, *values)
      ps = to_prepared_statement(type, values)
      db.prepared_statements[name] = ps if name
      ps
    end

### Protected Instance Methods

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

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

    # File lib/sequel/dataset/prepared_statements.rb, line 211
    def to_prepared_statement(type, values=nil)
      ps = bind
      ps.extend(PreparedStatementMethods)
      ps.prepared_type = type
      ps.prepared_modify_values = values
      ps
    end

## Methods that describe what the dataset supports ↑ top

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

### Constants

WITH_SUPPORTED

  Method used to check if WITH is supported

### Public Instance Methods

provides_accurate_rows_matched?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 20
    def provides_accurate_rows_matched?
      true
    end

quote_identifiers?() click to toggle source

Whether this dataset quotes identifiers.

    # File lib/sequel/dataset/features.rb, line 13
    def quote_identifiers?
      @quote_identifiers
    end

requires_sql_standard_datetimes?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 26
    def requires_sql_standard_datetimes?
      false
    end

supports_cte?() click to toggle source

Whether the dataset supports common table expressions (the WITH clause).

    # File lib/sequel/dataset/features.rb, line 31
    def supports_cte?
      select_clause_methods.include?(WITH_SUPPORTED)
    end

supports_distinct_on?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 36
    def supports_distinct_on?
      false
    end

supports_intersect_except?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 41
    def supports_intersect_except?
      true
    end

supports_intersect_except_all?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 46
    def supports_intersect_except_all?
      true
    end

supports_is_true?() click to toggle source

Whether the dataset supports the IS TRUE syntax.

    # File lib/sequel/dataset/features.rb, line 51
    def supports_is_true?
      true
    end

supports_join_using?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 56
    def supports_join_using?
      true
    end

supports_modifying_joins?() click to toggle source

Whether modifying joined datasets is supported.

    # File lib/sequel/dataset/features.rb, line 61
    def supports_modifying_joins?
      false
    end

supports_multiple_column_in?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 67
    def supports_multiple_column_in?
      true
    end

supports_timestamp_timezones?() click to toggle source

Whether the dataset supports timezones in literal timestamps

    # File lib/sequel/dataset/features.rb, line 72
    def supports_timestamp_timezones?
      false
    end

supports_timestamp_usecs?() click to toggle source

Whether the dataset supports fractional seconds in literal timestamps

    # File lib/sequel/dataset/features.rb, line 77
    def supports_timestamp_usecs?
      true
    end

supports_window_functions?() click to toggle source

Whether the dataset supports window functions.

    # File lib/sequel/dataset/features.rb, line 82
    def supports_window_functions?
      false
    end

## Methods that execute code on the database ↑ top

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

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

### Public Instance Methods

<<(*args) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 18
    def <<(*args)
      insert(*args)
    end

[](*conditions) click to toggle source

Returns the first record matching the conditions. Examples:

    ds[:id=>1] => {:id=1}

    # File lib/sequel/dataset/actions.rb, line 25
    def [](*conditions)
      raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
      first(*conditions)
    end

[]=(conditions, values) click to toggle source

Update all records matching the conditions with the values specified. Examples:

    ds[:id=>1] = {:id=>2} # SQL: UPDATE ... SET id = 2 WHERE id = 1

    # File lib/sequel/dataset/actions.rb, line 34
    def []=(conditions, values)
      filter(conditions).update(values)
    end

all(&block) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 40
    def all(&block)
      a = []
      each{|r| a << r}
      post_load(a)
      a.each(&block) if block
      a
    end

avg(column) click to toggle source

Returns the average value for the given column.

    # File lib/sequel/dataset/actions.rb, line 49
    def avg(column)
      aggregate_dataset.get{avg(column)}
    end

columns() click to toggle source

Returns the columns in the result set in order. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to get a single row. Adapters are expected to fill the columns cache with the column information when a query is performed. If the dataset does not have any rows, this may be an empty array depending on how the adapter is programmed.

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

    # File lib/sequel/dataset/actions.rb, line 62
    def columns
      return @columns if @columns
      ds = unfiltered.unordered.clone(:distinct => nil, :limit => 1)
      ds.each{break}
      @columns = ds.instance_variable_get(:@columns)
      @columns || []
    end

columns!() click to toggle source

Remove the cached list of columns and do a SELECT query to find the columns.

    # File lib/sequel/dataset/actions.rb, line 72
    def columns!
      @columns = nil
      columns
    end

count() click to toggle source

Returns the number of records in the dataset.

    # File lib/sequel/dataset/actions.rb, line 78
    def count
      aggregate_dataset.get{COUNT(:*){}.as(count)}.to_i
    end

delete() click to toggle source

Deletes the records in the dataset. The returned value is generally the number of records deleted, but that is adapter dependent. See delete_sql.

    # File lib/sequel/dataset/actions.rb, line 84
    def delete
      execute_dui(delete_sql)
    end

each(&block) click to toggle source

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

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 use should all instead of each.

    # File lib/sequel/dataset/actions.rb, line 94
    def each(&block)
      if @opts[:graph]
        graph_each(&block)
      elsif row_proc = @row_proc
        fetch_rows(select_sql){|r| yield row_proc.call(r)}
      else
        fetch_rows(select_sql, &block)
      end
      self
    end

empty?() click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 106
    def empty?
      get(1).nil?
    end

fetch_rows(sql, &block) click to toggle source

Executes a select query and fetches records, passing each record to the supplied block. The yielded records should be hashes with symbol keys.

    # File lib/sequel/dataset/actions.rb, line 112
    def fetch_rows(sql, &block)
      raise NotImplemented, NOTIMPL_MSG
    end

first(*args, &block) click to toggle source

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:

    ds.first => {:id=>7}
    ds.first(2) => [{:id=>6}, {:id=>4}]
    ds.order(:id).first(2) => [{:id=>1}, {:id=>2}]
    ds.first(:id=>2) => {:id=>2}
    ds.first("id = 3") => {:id=>3}
    ds.first("id = ?", 4) => {:id=>4}
    ds.first{|o| o.id > 2} => {:id=>5}
    ds.order(:id).first{|o| o.id > 2} => {:id=>3}
    ds.first{|o| o.id > 2} => {:id=>5}
    ds.first("id > ?", 4){|o| o.id < 6} => {:id=>5}
    ds.order(:id).first(2){|o| o.id < 2} => [{:id=>1}]

    # File lib/sequel/dataset/actions.rb, line 135
    def first(*args, &block)
      ds = block ? filter(&block) : self

      if args.empty?
        ds.single_record
      else
        args = (args.size == 1) ? args.first : args
        if Integer === args
          ds.limit(args).all
        else
          ds.filter(args).single_record
        end
      end
    end

get(column=nil, &block) click to toggle source

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

    ds.get(:id)
    ds.get{|o| o.sum(:id)}

    # File lib/sequel/dataset/actions.rb, line 155
    def get(column=nil, &block)
      if column
        raise(Error, ARG_BLOCK_ERROR_MSG) if block
        select(column).single_value
      else
        select(&block).single_value
      end
    end

import(columns, values, opts={}) click to toggle source

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

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

    dataset.import([:x, :y], [[1, 2], [3, 4]])

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

    dataset.import([:x, :y], other_dataset.select(:a___x, :b___y))

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)

    # File lib/sequel/dataset/actions.rb, line 183
    def import(columns, values, opts={})
      return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)

      return if values.empty?
      raise(Error, IMPORT_ERROR_MSG) if columns.empty?

      if slice_size = opts[:commit_every] || opts[:slice]
        offset = 0
        loop do
          @db.transaction(opts){multi_insert_sql(columns, values[offset, slice_size]).each{|st| execute_dui(st)}}
          offset += slice_size
          break if offset >= values.length
        end
      else
        statements = multi_insert_sql(columns, values)
        @db.transaction{statements.each{|st| execute_dui(st)}}
      end
    end

insert(*values) click to toggle source

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. See insert_sql.

    # File lib/sequel/dataset/actions.rb, line 205
    def insert(*values)
      execute_insert(insert_sql(*values))
    end

insert_multiple(array, &block) click to toggle source

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.

    # File lib/sequel/dataset/actions.rb, line 213
    def insert_multiple(array, &block)
      if block
        array.each {|i| insert(block[i])}
      else
        array.each {|i| insert(i)}
      end
    end

interval(column) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 223
    def interval(column)
      aggregate_dataset.get{max(column) - min(column)}
    end

last(*args, &block) click to toggle source

Reverses the order and then runs first. 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.

    # File lib/sequel/dataset/actions.rb, line 231
    def last(*args, &block)
      raise(Error, 'No order specified') unless @opts[:order]
      reverse.first(*args, &block)
    end

map(column=nil, &block) click to toggle source

Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of Enumerable. Raises an error if both an argument and block are given. Examples:

    ds.map(:id) => [1, 2, 3, ...]
    ds.map{|r| r[:id] * 2} => [2, 4, 6, ...]

    # File lib/sequel/dataset/actions.rb, line 242
    def map(column=nil, &block)
      if column
        raise(Error, ARG_BLOCK_ERROR_MSG) if block
        super(){|r| r[column]}
      else
        super(&block)
      end
    end

max(column) click to toggle source

Returns the maximum value for the given column.

    # File lib/sequel/dataset/actions.rb, line 252
    def max(column)
      aggregate_dataset.get{max(column)}
    end

min(column) click to toggle source

Returns the minimum value for the given column.

    # File lib/sequel/dataset/actions.rb, line 257
    def min(column)
      aggregate_dataset.get{min(column)}
    end

multi_insert(hashes, opts={}) click to toggle source

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

    dataset.multi_insert([{:x => 1}, {:x => 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.

    # File lib/sequel/dataset/actions.rb, line 271
    def multi_insert(hashes, opts={})
      return if hashes.empty?
      columns = hashes.first.keys
      import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
    end

range(column) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 279
    def range(column)
      if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first
        (r[:v1]..r[:v2])
      end
    end

select_hash(key_column, value_column) click to toggle source

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.

    # File lib/sequel/dataset/actions.rb, line 287
    def select_hash(key_column, value_column)
      select(key_column, value_column).to_hash(hash_key_symbol(key_column), hash_key_symbol(value_column))
    end

select_map(column=nil, &block) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 295
    def select_map(column=nil, &block)
      ds = naked.ungraphed
      ds = if column
        raise(Error, ARG_BLOCK_ERROR_MSG) if block
        ds.select(column)
      else
        ds.select(&block)
      end
      ds.map{|r| r.values.first}
    end

select_order_map(column=nil, &block) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 307
    def select_order_map(column=nil, &block)
      ds = naked.ungraphed
      ds = if column
        raise(Error, ARG_BLOCK_ERROR_MSG) if block
        ds.select(column).order(unaliased_identifier(column))
      else
        ds.select(&block).order(&block)
      end
      ds.map{|r| r.values.first}
    end

set(*args) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 320
    def set(*args)
      update(*args)
    end

single_record() click to toggle source

Returns the first record in the dataset.

    # File lib/sequel/dataset/actions.rb, line 325
    def single_record
      clone(:limit=>1).each{|r| return r}
      nil
    end

single_value() click to toggle source

Returns the first value of the first record in the dataset. Returns nil if dataset is empty.

    # File lib/sequel/dataset/actions.rb, line 332
    def single_value
      if r = naked.ungraphed.single_record
        r.values.first
      end
    end

sum(column) click to toggle source

Returns the sum for the given column.

    # File lib/sequel/dataset/actions.rb, line 339
    def sum(column)
      aggregate_dataset.get{sum(column)}
    end

to_csv(include_column_titles = true) click to toggle source

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.

    # File lib/sequel/dataset/actions.rb, line 351
    def to_csv(include_column_titles = true)
      n = naked
      cols = n.columns
      csv = ''
      csv << "#{cols.join(COMMA_SEPARATOR)}\r\n" if include_column_titles
      n.each{|r| csv << "#{cols.collect{|c| r[c]}.join(COMMA_SEPARATOR)}\r\n"}
      csv
    end

to_hash(key_column, value_column = nil) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 364
    def to_hash(key_column, value_column = nil)
      inject({}) do |m, r|
        m[r[key_column]] = value_column ? r[value_column] : r
        m
      end
    end

truncate() click to toggle source

Truncates the dataset. Returns nil.

    # File lib/sequel/dataset/actions.rb, line 372
    def truncate
      execute_ddl(truncate_sql)
    end

update(values={}) click to toggle source

Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent. See update_sql.

    # File lib/sequel/dataset/actions.rb, line 378
    def update(values={})
      execute_dui(update_sql(values))
    end

## Methods that return modified datasets ↑ top

These methods all return modified copies of the receiver.

### Constants

COLUMN_CHANGE_OPTS

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

CONDITIONED_JOIN_TYPES

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

JOIN_METHODS

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

NON_SQL_OPTIONS

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

QUERY_METHODS

  Methods that return modified datasets

UNCONDITIONED_JOIN_TYPES

  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.

### Public Instance Methods

and(*cond, &block) click to toggle source

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.

    ds.filter(:a).and(:b) # SQL: WHERE a AND b

    # File lib/sequel/dataset/query.rb, line 43
    def and(*cond, &block)
      raise(InvalidOperation, "No existing filter found.") unless @opts[:having] || @opts[:where]
      filter(*cond, &block)
    end

clone(opts = {}) click to toggle source

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.

    # File lib/sequel/dataset/query.rb, line 51
    def clone(opts = {})
      c = super()
      c.opts = @opts.merge(opts)
      c.instance_variable_set(:@columns, nil) if opts.keys.any?{|o| COLUMN_CHANGE_OPTS.include?(o)}
      c
    end

distinct(*args) click to toggle source

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

    dataset.distinct # SQL: SELECT DISTINCT * FROM items
    dataset.order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id

    # File lib/sequel/dataset/query.rb, line 67
    def distinct(*args)
      raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on?
      clone(:distinct => args)
    end

except(dataset, opts={}) click to toggle source

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

- :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.except(DB).sql #=> "SELECT * FROM items EXCEPT SELECT * FROM other_items"

    # File lib/sequel/dataset/query.rb, line 82
    def except(dataset, opts={})
      opts = {:all=>opts} unless opts.is_a?(Hash)
      raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
      raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
      compound_clone(:except, dataset, opts)
    end

exclude(*cond, &block) click to toggle source

Performs the inverse of Dataset#filter.

    dataset.exclude(:category => 'software').sql #=>
      "SELECT * FROM items WHERE (category != 'software')"

    # File lib/sequel/dataset/query.rb, line 93
    def exclude(*cond, &block)
      clause = (@opts[:having] ? :having : :where)
      cond = cond.first if cond.size == 1
      cond = filter_expr(cond, &block)
      cond = SQL::BooleanExpression.invert(cond)
      cond = SQL::BooleanExpression.new(:AND, @opts[clause], cond) if @opts[clause]
      clone(clause => cond)
    end

filter(*cond, &block) click to toggle source

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.

- 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:

    dataset.filter(:id => 3).sql #=>
      "SELECT * FROM items WHERE (id = 3)"
    dataset.filter('price < ?', 100).sql #=>
      "SELECT * FROM items WHERE price < 100"
    dataset.filter([[:id, (1,2,3)], [:id, 0..10]]).sql #=>
      "SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))"
    dataset.filter('price < 100').sql #=>
      "SELECT * FROM items WHERE price < 100"
    dataset.filter(:active).sql #=>
      "SELECT * FROM items WHERE :active
    dataset.filter{|o| o.price < 100}.sql #=>
      "SELECT * FROM items WHERE (price < 100)"

Multiple filter calls can be chained for scoping:

    software = dataset.filter(:category => 'software')
    software.filter{|o| o.price < 100}.sql #=>
      "SELECT * FROM items WHERE ((category = 'software') AND (price < 100))"

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

    # File lib/sequel/dataset/query.rb, line 150
    def filter(*cond, &block)
      _filter(@opts[:having] ? :having : :where, *cond, &block)
    end

for_update() click to toggle source

Returns a cloned dataset with a :update lock style.

    # File lib/sequel/dataset/query.rb, line 155
    def for_update
      lock_style(:update)
    end

from(*source) click to toggle source

Returns a copy of the dataset with the source changed.

    dataset.from # SQL: SELECT *
    dataset.from(:blah) # SQL: SELECT * FROM blah
    dataset.from(:blah, :foo) # SQL: SELECT * FROM blah, foo

    # File lib/sequel/dataset/query.rb, line 164
    def from(*source)
      table_alias_num = 0
      sources = []
      source.each do |s|
        case s
        when Hash
          s.each{|k,v| sources << SQL::AliasedExpression.new(k,v)}
        when Dataset
          sources << SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
        when Symbol
          sch, table, aliaz = split_symbol(s)
          if aliaz
            s = sch ? SQL::QualifiedIdentifier.new(sch.to_sym, table.to_sym) : SQL::Identifier.new(table.to_sym)
            sources << SQL::AliasedExpression.new(s, aliaz.to_sym)
          else
            sources << s
          end
        else
          sources << s
        end
      end
      o = {:from=>sources.empty? ? nil : sources}
      o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
      clone(o)
    end

from_self(opts={}) click to toggle source

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

    ds = DB[:items].order(:name).select(:id, :name)
    ds.sql                         #=> "SELECT id,name FROM items ORDER BY name"
    ds.from_self.sql               #=> "SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS t1"
    ds.from_self(:alias=>:foo).sql #=> "SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo"

    # File lib/sequel/dataset/query.rb, line 197
    def from_self(opts={})
      fs = {}
      @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)}
      clone(fs).from(opts[:alias] ? as(opts[:alias]) : self)
    end

grep(cols, terms) click to toggle source

Pattern match any of the columns to any of the terms. The terms can be strings (which use LIKE) or regular expressions (which are only supported in some databases). See Sequel::SQL::StringExpression.like. Note that the total number of pattern matches will be cols.length * terms.length, which could cause performance issues.

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

    # File lib/sequel/dataset/query.rb, line 211
    def grep(cols, terms)
      filter(SQL::BooleanExpression.new(:OR, *Array(cols).collect{|c| SQL::StringExpression.like(c, *terms)}))
    end

group(*columns) click to toggle source

Returns a copy of the dataset with the results grouped by the value of the given columns.

    dataset.group(:id) # SELECT * FROM items GROUP BY id
    dataset.group(:id, :name) # SELECT * FROM items GROUP BY id, name

    # File lib/sequel/dataset/query.rb, line 220
    def group(*columns)
      clone(:group => (columns.compact.empty? ? nil : columns))
    end

group_and_count(*columns) click to toggle source

Returns a dataset grouped by the given column with count by group, order by the count of records. Column aliases may be supplied, and will be included in the select clause.

Examples:

    ds.group_and_count(:name).all => [{:name=>'a', :count=>1}, ...]
    ds.group_and_count(:first_name, :last_name).all => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...]
    ds.group_and_count(:first_name___name).all => [{:name=>'a', :count=>1}, ...]

    # File lib/sequel/dataset/query.rb, line 238
    def group_and_count(*columns)
      group(*columns.map{|c| unaliased_identifier(c)}).select(*(columns + [COUNT_OF_ALL_AS_COUNT]))
    end

group_by(*columns) click to toggle source

Alias of group

    # File lib/sequel/dataset/query.rb, line 225
    def group_by(*columns)
      group(*columns)
    end

having(*cond, &block) click to toggle source

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

    dataset.group(:sum).having(:sum=>10) # SQL: SELECT * FROM items GROUP BY sum HAVING sum = 10

    # File lib/sequel/dataset/query.rb, line 245
    def having(*cond, &block)
      _filter(:having, *cond, &block)
    end

intersect(dataset, opts={}) click to toggle source

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

- :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.intersect(DB).sql #=> "SELECT * FROM items INTERSECT SELECT * FROM other_items"

    # File lib/sequel/dataset/query.rb, line 259
    def intersect(dataset, opts={})
      opts = {:all=>opts} unless opts.is_a?(Hash)
      raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
      raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
      compound_clone(:intersect, dataset, opts)
    end

invert() click to toggle source

Inverts the current filter

    dataset.filter(:category => 'software').invert.sql #=>
      "SELECT * FROM items WHERE (category != 'software')"

    # File lib/sequel/dataset/query.rb, line 270
    def invert
      having, where = @opts[:having], @opts[:where]
      raise(Error, "No current filter") unless having || where
      o = {}
      o[:having] = SQL::BooleanExpression.invert(having) if having
      o[:where] = SQL::BooleanExpression.invert(where) if where
      clone(o)
    end

join(*args, &block) click to toggle source

Alias of inner_join

    # File lib/sequel/dataset/query.rb, line 280
    def join(*args, &block)
      inner_join(*args, &block)
    end

join_table(type, table, expr=nil, options={}, &block) click to toggle source

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

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

  - nil - If a block is not given, doesn’t use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses a 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 blockless filter 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.

    # File lib/sequel/dataset/query.rb, line 314
    def join_table(type, table, expr=nil, options={}, &block)
      using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
      if using_join && !supports_join_using?
        h = {}
        expr.each{|s| h[s] = s}
        return join_table(type, table, h, options)
      end

      case options
      when Hash
        table_alias = options[:table_alias]
        last_alias = options[:implicit_qualifier]
      when Symbol, String, SQL::Identifier
        table_alias = options
        last_alias = nil
      else
        raise Error, "invalid options format for join_table: #{options.inspect}"
      end

      if Dataset === table
        if table_alias.nil?
          table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
          table_alias = dataset_alias(table_alias_num)
        end
        table_name = table_alias
      else
        table = table.table_name if table.respond_to?(:table_name)
        table_name = table_alias || table
      end

      join = if expr.nil? and !block_given?
        SQL::JoinClause.new(type, table, table_alias)
      elsif using_join
        raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block_given?
        SQL::JoinUsingClause.new(expr, type, table, table_alias)
      else
        last_alias ||= @opts[:last_joined_table] || first_source_alias
        if Sequel.condition_specifier?(expr)
          expr = expr.collect do |k, v|
            k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
            v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
            [k,v]
          end
        end
        if block_given?
          expr2 = yield(table_name, last_alias, @opts[:join] || [])
          expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
        end
        SQL::JoinOnClause.new(expr, type, table, table_alias)
      end

      opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name}
      opts[:num_dataset_sources] = table_alias_num if table_alias_num
      clone(opts)
    end

limit(l, o = nil) click to toggle source

If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset.

    dataset.limit(10) # SQL: SELECT * FROM items LIMIT 10
    dataset.limit(10, 20) # SQL: SELECT * FROM items LIMIT 10 OFFSET 20

    # File lib/sequel/dataset/query.rb, line 383
    def limit(l, o = nil)
      return from_self.limit(l, o) if @opts[:sql]

      if Range === l
        o = l.first
        l = l.last - l.first + (l.exclude_end? ? 0 : 1)
      end
      l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
      if l.is_a?(Integer)
        raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
      end
      opts = {:limit => l}
      if o
        o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
        if o.is_a?(Integer)
          raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
        end
        opts[:offset] = o
      end
      clone(opts)
    end

lock_style(style) click to toggle source

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

    # File lib/sequel/dataset/query.rb, line 409
    def lock_style(style)
      clone(:lock => style)
    end

naked() click to toggle source

Returns a naked dataset clone - i.e. a dataset that returns records as hashes instead of calling the row proc.

    # File lib/sequel/dataset/query.rb, line 415
    def naked
      ds = clone
      ds.row_proc = nil
      ds
    end

or(*cond, &block) click to toggle source

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

    dataset.filter(:a).or(:b) # SQL: SELECT * FROM items WHERE a OR b

    # File lib/sequel/dataset/query.rb, line 425
    def or(*cond, &block)
      clause = (@opts[:having] ? :having : :where)
      raise(InvalidOperation, "No existing filter found.") unless @opts[clause]
      cond = cond.first if cond.size == 1
      clone(clause => SQL::BooleanExpression.new(:OR, @opts[clause], filter_expr(cond, &block)))
    end

order(*columns, &block) click to toggle source

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

    ds.order(:name).sql #=> 'SELECT * FROM items ORDER BY name'
    ds.order(:a, :b).sql #=> 'SELECT * FROM items ORDER BY a, b'
    ds.order('a + b'.lit).sql #=> 'SELECT * FROM items ORDER BY a + b'
    ds.order(:a + :b).sql #=> 'SELECT * FROM items ORDER BY (a + b)'
    ds.order(:name.desc).sql #=> 'SELECT * FROM items ORDER BY name DESC'
    ds.order(:name.asc).sql #=> 'SELECT * FROM items ORDER BY name ASC'
    ds.order{|o| o.sum(:name)}.sql #=> 'SELECT * FROM items ORDER BY sum(name)'
    ds.order(nil).sql #=> 'SELECT * FROM items'

    # File lib/sequel/dataset/query.rb, line 445
    def order(*columns, &block)
      columns += Array(Sequel.virtual_row(&block)) if block
      clone(:order => (columns.compact.empty?) ? nil : columns)
    end

order_append(*columns, &block) click to toggle source

Alias of order_more, for naming consistency with order_prepend.

    # File lib/sequel/dataset/query.rb, line 451
    def order_append(*columns, &block)
      order_more(*columns, &block)
    end

order_by(*columns, &block) click to toggle source

Alias of order

    # File lib/sequel/dataset/query.rb, line 456
    def order_by(*columns, &block)
      order(*columns, &block)
    end

order_more(*columns, &block) click to toggle source

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

    ds.order(:a).order(:b).sql #=> 'SELECT * FROM items ORDER BY b'
    ds.order(:a).order_more(:b).sql #=> 'SELECT * FROM items ORDER BY a, b'

    # File lib/sequel/dataset/query.rb, line 465
    def order_more(*columns, &block)
      columns = @opts[:order] + columns if @opts[:order]
      order(*columns, &block)
    end

order_prepend(*columns, &block) click to toggle source

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

    ds.order(:a).order(:b).sql #=> 'SELECT * FROM items ORDER BY b'
    ds.order(:a).order_prepend(:b).sql #=> 'SELECT * FROM items ORDER BY b, a'

    # File lib/sequel/dataset/query.rb, line 475
    def order_prepend(*columns, &block)
      ds = order(*columns, &block)
      @opts[:order] ? ds.order_more(*@opts[:order]) : ds
    end

qualify(table=first_source) click to toggle source

Qualify to the given table, or first source if not table is given.

    # File lib/sequel/dataset/query.rb, line 481
    def qualify(table=first_source)
      qualify_to(table)
    end

qualify_to(table) click to toggle source

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.

    # File lib/sequel/dataset/query.rb, line 489
    def qualify_to(table)
      o = @opts
      return clone if o[:sql]
      h = {}
      (o.keys & QUALIFY_KEYS).each do |k|
        h[k] = qualified_expression(o[k], table)
      end
      h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty?
      clone(h)
    end

qualify_to_first_source() click to toggle 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.

    # File lib/sequel/dataset/query.rb, line 505
    def qualify_to_first_source
      qualify_to(first_source)
    end

reverse(*order) click to toggle source

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

    # File lib/sequel/dataset/query.rb, line 511
    def reverse(*order)
      order(*invert_order(order.empty? ? @opts[:order] : order))
    end

reverse_order(*order) click to toggle source

Alias of reverse

    # File lib/sequel/dataset/query.rb, line 516
    def reverse_order(*order)
      reverse(*order)
    end

select(*columns, &block) click to toggle source

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

    dataset.select(:a) # SELECT a FROM items
    dataset.select(:a, :b) # SELECT a, b FROM items
    dataset.select{|o| [o.a, o.sum(:b)]} # SELECT a, sum(b) FROM items

    # File lib/sequel/dataset/query.rb, line 527
    def select(*columns, &block)
      columns += Array(Sequel.virtual_row(&block)) if block
      m = []
      columns.map do |i|
        i.is_a?(Hash) ? m.concat(i.map{|k, v| SQL::AliasedExpression.new(k,v)}) : m << i
      end
      clone(:select => m)
    end

select_all() click to toggle source

Returns a copy of the dataset selecting the wildcard.

    dataset.select(:a).select_all # SELECT * FROM items

    # File lib/sequel/dataset/query.rb, line 539
    def select_all
      clone(:select => nil)
    end

select_append(*columns, &block) click to toggle source

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

    dataset.select(:a).select(:b) # SELECT b FROM items
    dataset.select(:a).select_append(:b) # SELECT a, b FROM items
    dataset.select_append(:b) # SELECT *, b FROM items

    # File lib/sequel/dataset/query.rb, line 550
    def select_append(*columns, &block)
      cur_sel = @opts[:select]
      cur_sel = [WILDCARD] if !cur_sel || cur_sel.empty?
      select(*(cur_sel + columns), &block)
    end

select_more(*columns, &block) click to toggle source

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

    dataset.select(:a).select(:b) # SELECT b FROM items
    dataset.select(:a).select_more(:b) # SELECT a, b FROM items
    dataset.select_more(:b) # SELECT b FROM items

    # File lib/sequel/dataset/query.rb, line 563
    def select_more(*columns, &block)
      columns = @opts[:select] + columns if @opts[:select]
      select(*columns, &block)
    end

server(servr) click to toggle source

Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (which is SELECT uses :read_only database and all other queries use the :default database).

    # File lib/sequel/dataset/query.rb, line 571
    def server(servr)
      clone(:server=>servr)
    end

set_defaults(hash) click to toggle source

Set the default values for insert and update statements. The values hash passed to insert or update are merged into this hash.

    # File lib/sequel/dataset/query.rb, line 577
    def set_defaults(hash)
      clone(:defaults=>(@opts[:defaults]||{}).merge(hash))
    end

set_overrides(hash) click to toggle source

Set values that override hash arguments given to insert and update statements. This hash is merged into the hash provided to insert or update.

    # File lib/sequel/dataset/query.rb, line 583
    def set_overrides(hash)
      clone(:overrides=>hash.merge(@opts[:overrides]||{}))
    end

unfiltered() click to toggle source

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

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

    # File lib/sequel/dataset/query.rb, line 590
    def unfiltered
      clone(:where => nil, :having => nil)
    end

ungrouped() click to toggle source

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

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

    # File lib/sequel/dataset/query.rb, line 597
    def ungrouped
      clone(:group => nil, :having => nil)
    end

union(dataset, opts={}) click to toggle source

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

- :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.union(DB).sql #=> "SELECT * FROM items UNION SELECT * FROM other_items"

    # File lib/sequel/dataset/query.rb, line 610
    def union(dataset, opts={})
      opts = {:all=>opts} unless opts.is_a?(Hash)
      compound_clone(:union, dataset, opts)
    end

unlimited() click to toggle source

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

    dataset.limit(10, 20).unlimited # SELECT * FROM items

    # File lib/sequel/dataset/query.rb, line 618
    def unlimited
      clone(:limit=>nil, :offset=>nil)
    end

unordered() click to toggle source

Returns a copy of the dataset with no order.

    dataset.order(:a).unordered # SELECT * FROM items

    # File lib/sequel/dataset/query.rb, line 625
    def unordered
      order(nil)
    end

where(*cond, &block) click to toggle source

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

    dataset.group(:a).having(:a).filter(:b) # SELECT * FROM items GROUP BY a HAVING a AND b
    dataset.group(:a).having(:a).where(:b) # SELECT * FROM items WHERE b GROUP BY a HAVING a

    # File lib/sequel/dataset/query.rb, line 633
    def where(*cond, &block)
      _filter(:where, *cond, &block)
    end

with(name, dataset, opts={}) click to toggle source

Add a simple 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

    # File lib/sequel/dataset/query.rb, line 642
    def with(name, dataset, opts={})
      raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
      clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)])
    end

with_recursive(name, nonrecursive, recursive, opts={}) click to toggle source

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

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

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

    # File lib/sequel/dataset/query.rb, line 652
    def with_recursive(name, nonrecursive, recursive, opts={})
      raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
      clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))])
    end

with_sql(sql, *args) click to toggle source

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

    dataset.with_sql('SELECT * FROM foo') # SELECT * FROM foo

    # File lib/sequel/dataset/query.rb, line 661
    def with_sql(sql, *args)
      sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
      clone(:sql=>sql)
    end

### Protected Instance Methods

options_overlap(opts) click to toggle source

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

    # File lib/sequel/dataset/query.rb, line 669
    def options_overlap(opts)
      !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty?
    end

simple_select_all?() click to toggle source

Whether this dataset is a simple SELECT * FROM table.

    # File lib/sequel/dataset/query.rb, line 674
    def simple_select_all?
      o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)}
      o.length == 1 && (f = o[:from]) && f.length == 1 && f.first.is_a?(Symbol)
    end

## Miscellaneous methods ↑ top

These methods don’t fit cleanly into another section.

### Constants

ARG_BLOCK_ERROR_MSG
ARRAY_ACCESS_ERROR_MSG
IMPORT_ERROR_MSG
NOTIMPL_MSG

### Attributes

db[RW]

The database that corresponds to this dataset

opts[RW]

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

### Public Class Methods

new(db, opts = nil) click to toggle source

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

    DB[:posts]

Sequel::Dataset is an abstract class that is not useful by itself. Each database adaptor should provide a subclass of Sequel::Dataset, and have the Database#dataset method return an instance of that class.

    # File lib/sequel/dataset/misc.rb, line 27
    def initialize(db, opts = nil)
      @db = db
      @quote_identifiers = db.quote_identifiers? if db.respond_to?(:quote_identifiers?)
      @identifier_input_method = db.identifier_input_method if db.respond_to?(:identifier_input_method)
      @identifier_output_method = db.identifier_output_method if db.respond_to?(:identifier_output_method)
      @opts = opts || {}
      @row_proc = nil
    end

### Public Instance Methods

as(aliaz) click to toggle source

Return the dataset as an aliased expression with the given alias. You can use this as a FROM or JOIN dataset, or as a column if this dataset returns a single row and column.

    # File lib/sequel/dataset/misc.rb, line 39
    def as(aliaz)
      ::Sequel::SQL::AliasedExpression.new(self, aliaz)
    end

each_page(page_size, &block) click to toggle source

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

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

each_server() click to toggle source

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

    DB[:configs].where(:key=>'setting').each_server{|ds| ds.update(:value=>'new_value')}

    # File lib/sequel/dataset/misc.rb, line 48
    def each_server
      db.servers.each{|s| yield server(s)}
    end

first_source() click to toggle source

Alias of first_source_alias

    # File lib/sequel/dataset/misc.rb, line 53
    def first_source
      first_source_alias
    end

first_source_alias() click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 59
    def first_source_alias
      source = @opts[:from]
      if source.nil? || source.empty?
        raise Error, 'No source specified for query'
      end
      case s = source.first
      when SQL::AliasedExpression
        s.aliaz
      when Symbol
        sch, table, aliaz = split_symbol(s)
        aliaz ? aliaz.to_sym : s
      else
        s
      end
    end

first_source_table() click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 78
    def first_source_table
      source = @opts[:from]
      if source.nil? || source.empty?
        raise Error, 'No source specified for query'
      end
      case s = source.first
      when SQL::AliasedExpression
        s.expression
      when Symbol
        sch, table, aliaz = split_symbol(s)
        aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
      else
        s
      end
    end

inspect() click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 96
    def inspect
      "#<#{self.class}: #{sql.inspect}>"
    end

paginate(page_no, page_size, record_count=nil) click to toggle source

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.

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

print(*cols) click to toggle source

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

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

query(&block) click to toggle source

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.

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

unused_table_alias(table_alias) click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 106
    def unused_table_alias(table_alias)
      table_alias = alias_symbol(table_alias)
      used_aliases = []
      used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
      used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
      if used_aliases.include?(table_alias)
        i = 0
        loop do
          ta = :"#{table_alias}_#{i}"
          return ta unless used_aliases.include?(ta)
          i += 1
        end
      else
        table_alias
      end
    end

## Mutation methods ↑ top

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

### Constants

MUTATION_METHODS

  All methods that should have a ! method added that modifies the receiver.

### Attributes

identifier_input_method[RW]

Set the method to call on identifiers going into the database for this dataset

identifier_output_method[RW]

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 a Proc that takes a single hash argument and returns the object you want each to return.

### Public Class Methods

def_mutation_method(*meths) click to toggle source

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.

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

### Public Instance Methods

def_mutation_method(*meths) click to toggle source

Add a mutation method to this dataset instance.

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

## User Methods relating to SQL Creation ↑ top

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

### Public Instance Methods

delete_sql() click to toggle source

Formats a DELETE statement using the given options and dataset options.

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

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

exists() click to toggle source

Returns an EXISTS clause for the dataset as a LiteralString.

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

    # File lib/sequel/dataset/sql.rb, line 22
    def exists
      LiteralString.new("EXISTS (#{select_sql})")
    end

insert_sql(*values) click to toggle source

Formats an INSERT statement using the given values. The API is a little complex, and best explained by example:

    # Default values
    DB[:items].insert_sql #=> 'INSERT INTO items DEFAULT VALUES'
    DB[:items].insert_sql({}) #=> 'INSERT INTO items DEFAULT VALUES'
    # Values without columns
    DB[:items].insert_sql(1,2,3) #=> 'INSERT INTO items VALUES (1, 2, 3)'
    DB[:items].insert_sql([1,2,3]) #=> 'INSERT INTO items VALUES (1, 2, 3)'
    # Values with columns
    DB[:items].insert_sql([:a, :b], [1,2]) #=> 'INSERT INTO items (a, b) VALUES (1, 2)'
    DB[:items].insert_sql(:a => 1, :b => 2) #=> 'INSERT INTO items (a, b) VALUES (1, 2)'
    # Using a subselect
    DB[:items].insert_sql(DB[:old_items]) #=> 'INSERT INTO items SELECT * FROM old_items
    # Using a subselect with columns
    DB[:items].insert_sql([:a, :b], DB[:old_items]) #=> 'INSERT INTO items (a, b) SELECT * FROM old_items

    # File lib/sequel/dataset/sql.rb, line 42
    def insert_sql(*values)
      return static_sql(@opts[:sql]) if @opts[:sql]

      check_modification_allowed!

      columns = []

      case values.size
      when 0
        return insert_sql({})
      when 1
        case vals = values.at(0)
        when Hash
          vals = @opts[:defaults].merge(vals) if @opts[:defaults]
          vals = vals.merge(@opts[:overrides]) if @opts[:overrides]
          values = []
          vals.each do |k,v|
            columns << k
            values << v
          end
        when Dataset, Array, LiteralString
          values = vals
        else
          if vals.respond_to?(:values) && (v = vals.values).is_a?(Hash)
            return insert_sql(v)
          end
        end
      when 2
        if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
          columns, values = v0, v1
          raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
        end
      end

      columns = columns.map{|k| literal(String === k ? k.to_sym : k)}
      clone(:columns=>columns, :values=>values)._insert_sql
    end

literal(v) click to toggle source

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

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

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

    # File lib/sequel/dataset/sql.rb, line 90
    def literal(v)
      case v
      when String
        return v if v.is_a?(LiteralString)
        v.is_a?(SQL::Blob) ? literal_blob(v) : literal_string(v)
      when Symbol
        literal_symbol(v)
      when Integer
        literal_integer(v)
      when Hash
        literal_hash(v)
      when SQL::Expression
        literal_expression(v)
      when Float
        literal_float(v)
      when BigDecimal
        literal_big_decimal(v)
      when NilClass
        literal_nil
      when TrueClass
        literal_true
      when FalseClass
        literal_false
      when Array
        literal_array(v)
      when Time
        literal_time(v)
      when DateTime
        literal_datetime(v)
      when Date
        literal_date(v)
      when Dataset
        literal_dataset(v)
      else
        literal_other(v)
      end
    end

multi_insert_sql(columns, values) click to toggle source

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

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

    # File lib/sequel/dataset/sql.rb, line 134
    def multi_insert_sql(columns, values)
      values.map{|r| insert_sql(columns, r)}
    end

select_sql() click to toggle source

Formats a SELECT statement

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

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

sql() click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 147
    def sql
      select_sql
    end

truncate_sql() click to toggle source

SQL query to truncate the table

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

update_sql(values = {}) click to toggle source

Formats an UPDATE statement using the given values.

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

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

    # File lib/sequel/dataset/sql.rb, line 169
    def update_sql(values = {})
      return static_sql(opts[:sql]) if opts[:sql]
      check_modification_allowed!
      clone(:values=>values)._update_sql
    end

[Validate]

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