### Home Classes Methods

### In Files

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

### Parent

Object

### Sections

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

### Namespace

- MODULE Sequel::Dataset::ArgumentMapper
- MODULE Sequel::Dataset::NullDataset
- MODULE Sequel::Dataset::Nullifiable
- MODULE Sequel::Dataset::Pagination
- MODULE Sequel::Dataset::PreparedStatementMethods
- MODULE Sequel::Dataset::Replace
- MODULE Sequel::Dataset::SplitArrayNil
- MODULE Sequel::Dataset::StoredProcedureMethods
- MODULE Sequel::Dataset::StoredProcedures
- MODULE Sequel::Dataset::UnnumberedArgumentMapper
- CLASS Sequel::Dataset::PlaceholderLiteralizer
- CLASS Sequel::Dataset::Query

### Methods

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

### Included Modules

- Enumerable
- Sequel::SQL::AliasMethods
- Sequel::SQL::BooleanMethods
- Sequel::SQL::CastMethods
- Sequel::SQL::ComplexExpressionMethods
- Sequel::SQL::InequalityMethods
- Sequel::SQL::NumericMethods
- Sequel::SQL::OrderMethods
- Sequel::SQL::StringMethods

### Files

- CHANGELOG
- MIT-LICENSE
- README.rdoc
- active_record.rdoc
- advanced_associations.rdoc
- association_basics.rdoc
- bin_sequel.rdoc
- cheat_sheet.rdoc
- code_order.rdoc
- core_extensions.rdoc
- dataset_basics.rdoc
- dataset_filtering.rdoc
- extensions.rdoc
- mass_assignment.rdoc
- migration.rdoc
- model_hooks.rdoc
- model_plugins.rdoc
- mssql_stored_procedures.rdoc
- object_model.rdoc
- opening_databases.rdoc
- postgresql.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
- 3.13.0.txt
- 3.14.0.txt
- 3.15.0.txt
- 3.16.0.txt
- 3.17.0.txt
- 3.18.0.txt
- 3.19.0.txt
- 3.2.0.txt
- 3.20.0.txt
- 3.21.0.txt
- 3.22.0.txt
- 3.23.0.txt
- 3.24.0.txt
- 3.25.0.txt
- 3.26.0.txt
- 3.27.0.txt
- 3.28.0.txt
- 3.29.0.txt
- 3.3.0.txt
- 3.30.0.txt
- 3.31.0.txt
- 3.32.0.txt
- 3.33.0.txt
- 3.34.0.txt
- 3.35.0.txt
- 3.36.0.txt
- 3.37.0.txt
- 3.38.0.txt
- 3.39.0.txt
- 3.4.0.txt
- 3.40.0.txt
- 3.41.0.txt
- 3.42.0.txt
- 3.43.0.txt
- 3.44.0.txt
- 3.45.0.txt
- 3.46.0.txt
- 3.47.0.txt
- 3.48.0.txt
- 3.5.0.txt
- 3.6.0.txt
- 3.7.0.txt
- 3.8.0.txt
- 3.9.0.txt
- 4.0.0.txt
- 4.1.0.txt
- 4.10.0.txt
- 4.11.0.txt
- 4.2.0.txt
- 4.3.0.txt
- 4.4.0.txt
- 4.5.0.txt
- 4.6.0.txt
- 4.7.0.txt
- 4.8.0.txt
- 4.9.0.txt
- schema_modification.rdoc
- security.rdoc
- sharding.rdoc
- sql.rdoc
- testing.rdoc
- thread_safety.rdoc
- transactions.rdoc
- validations.rdoc
- virtual_rows.rdoc

### Class/Module Index

Quicksearch

- Sequel
- Sequel::ADO
- Sequel::ADO::Access
- Sequel::ADO::Access::AdoSchema
- Sequel::ADO::Access::AdoSchema::Column
- Sequel::ADO::Access::DatabaseMethods
- Sequel::ADO::Access::Dataset
- Sequel::ADO::Database
- Sequel::ADO::Dataset
- Sequel::ADO::MSSQL
- Sequel::ADO::MSSQL::DatabaseMethods
- Sequel::ADO::MSSQL::Dataset
- Sequel::ASTTransformer
- Sequel::Access
- Sequel::Access::DatabaseMethods
- Sequel::Access::DatasetMethods
- Sequel::AdapterNotFound
- Sequel::Amalgalite
- Sequel::Amalgalite::Database
- Sequel::Amalgalite::Dataset
- Sequel::Amalgalite::SequelTypeMap
- Sequel::ArbitraryServers
- Sequel::BasicObject
- Sequel::BeforeHookFailed
- Sequel::CheckConstraintViolation
- Sequel::ColumnsIntrospection
- Sequel::ConnectionPool
- Sequel::ConnectionPool::ClassMethods
- Sequel::ConnectionValidator
- Sequel::ConnectionValidator::Retry
- Sequel::ConstraintValidations
- Sequel::ConstraintValidations::AlterTableGeneratorMethods
- Sequel::ConstraintValidations::CreateTableGeneratorMethods
- Sequel::ConstraintValidations::Generator
- Sequel::ConstraintViolation
- Sequel::CoreRefinements
- Sequel::Cubrid
- Sequel::Cubrid::Database
- Sequel::Cubrid::DatabaseMethods
- Sequel::Cubrid::Dataset
- Sequel::Cubrid::DatasetMethods
- Sequel::CurrentDateTimeTimestamp
- Sequel::CurrentDateTimeTimestamp::DatasetMethods
- Sequel::CurrentDateTimeTimestamp::DateTime
- Sequel::CurrentDateTimeTimestamp::Time
- Sequel::DB2
- Sequel::DB2::DB2Error
- Sequel::DB2::Database
- Sequel::DB2::DatabaseMethods
- Sequel::DB2::Dataset
- Sequel::DB2::DatasetMethods
- 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::DatabaseMethods
- Sequel::DataObjects::SQLite
- Sequel::DataObjects::SQLite::DatabaseMethods
- Sequel::Database
- Sequel::Database::FromBlock
- Sequel::Database::ResetIdentifierMangling
- Sequel::Database::SplitAlterTable
- Sequel::DatabaseConnectionError
- Sequel::DatabaseDisconnectError
- Sequel::DatabaseError
- Sequel::DatabaseQuery
- Sequel::Dataset
- Sequel::Dataset::ArgumentMapper
- Sequel::Dataset::NullDataset
- Sequel::Dataset::Nullifiable
- Sequel::Dataset::Pagination
- Sequel::Dataset::PlaceholderLiteralizer
- Sequel::Dataset::PlaceholderLiteralizer::Argument
- Sequel::Dataset::PlaceholderLiteralizer::Recorder
- Sequel::Dataset::PreparedStatementMethods
- Sequel::Dataset::Query
- Sequel::Dataset::Replace
- Sequel::Dataset::SplitArrayNil
- Sequel::Dataset::StoredProcedureMethods
- Sequel::Dataset::StoredProcedures
- Sequel::Dataset::UnnumberedArgumentMapper
- Sequel::DatasetPagination
- Sequel::DatasetPrinter
- Sequel::DatasetQuery
- Sequel::Deprecation
- Sequel::EmptyArrayIgnoreNulls
- Sequel::EmulateOffsetWithReverseAndCount
- Sequel::EmulateOffsetWithRowNumber
- Sequel::Error
- Sequel::Error::AdapterNotFound
- Sequel::Error::InvalidOperation
- Sequel::Error::InvalidValue
- Sequel::Error::PoolTimeoutError
- Sequel::Error::Rollback
- Sequel::ErrorSQL
- Sequel::EvalInspect
- Sequel::FilterHaving
- Sequel::Firebird
- Sequel::Firebird::Database
- Sequel::Firebird::DatabaseMethods
- Sequel::Firebird::Dataset
- Sequel::Firebird::DatasetMethods
- Sequel::ForeignKeyConstraintViolation
- Sequel::GraphEach
- Sequel::HashAliases
- Sequel::HookFailed
- Sequel::IBMDB
- Sequel::IBMDB::Connection
- Sequel::IBMDB::Connection::Error
- Sequel::IBMDB::Database
- Sequel::IBMDB::Dataset
- Sequel::IBMDB::Dataset::CallableStatementMethods
- Sequel::IBMDB::Dataset::PreparedStatementMethods
- Sequel::IBMDB::Statement
- Sequel::Inflections
- Sequel::Informix
- Sequel::Informix::Database
- Sequel::Informix::DatabaseMethods
- Sequel::Informix::Dataset
- Sequel::Informix::DatasetMethods
- Sequel::IntegerMigrator
- Sequel::InvalidOperation
- Sequel::InvalidValue
- Sequel::JDBC
- Sequel::JDBC::AS400
- Sequel::JDBC::AS400::DatabaseMethods
- Sequel::JDBC::AS400::Dataset
- Sequel::JDBC::Cubrid
- Sequel::JDBC::Cubrid::DatabaseMethods
- Sequel::JDBC::DB2
- Sequel::JDBC::DB2::DatabaseMethods
- Sequel::JDBC::DB2::Dataset
- Sequel::JDBC::Database
- Sequel::JDBC::Dataset
- Sequel::JDBC::Dataset::PreparedStatementMethods
- Sequel::JDBC::Dataset::StoredProcedureMethods
- Sequel::JDBC::Derby
- Sequel::JDBC::Derby::DatabaseMethods
- Sequel::JDBC::Derby::Dataset
- Sequel::JDBC::Firebird
- Sequel::JDBC::Firebird::DatabaseMethods
- Sequel::JDBC::H2
- Sequel::JDBC::H2::DatabaseMethods
- Sequel::JDBC::H2::Dataset
- Sequel::JDBC::HSQLDB
- Sequel::JDBC::HSQLDB::DatabaseMethods
- Sequel::JDBC::HSQLDB::Dataset
- Sequel::JDBC::Informix
- Sequel::JDBC::Informix::DatabaseMethods
- Sequel::JDBC::JTDS
- Sequel::JDBC::JTDS::DatabaseMethods
- Sequel::JDBC::JTDS::Dataset
- Sequel::JDBC::JavaLang
- Sequel::JDBC::JavaSQL
- Sequel::JDBC::JavaxNaming
- Sequel::JDBC::MSSQL
- Sequel::JDBC::MSSQL::DatabaseMethods
- Sequel::JDBC::MySQL
- Sequel::JDBC::MySQL::DatabaseMethods
- Sequel::JDBC::Oracle
- Sequel::JDBC::Oracle::DatabaseMethods
- Sequel::JDBC::Oracle::Dataset
- Sequel::JDBC::Postgres
- Sequel::JDBC::Postgres::DatabaseMethods
- Sequel::JDBC::Postgres::Dataset
- Sequel::JDBC::Progress
- Sequel::JDBC::Progress::DatabaseMethods
- Sequel::JDBC::SQLServer
- Sequel::JDBC::SQLServer::DatabaseMethods
- Sequel::JDBC::SQLServer::DatabaseMethods::MetadataDatasetMethods
- Sequel::JDBC::SQLite
- Sequel::JDBC::SQLite::DatabaseMethods
- Sequel::JDBC::SqlAnywhere
- Sequel::JDBC::SqlAnywhere::DatabaseMethods
- Sequel::JDBC::SqlAnywhere::Dataset
- Sequel::JDBC::Transactions
- Sequel::JDBC::TypeConvertor
- Sequel::LiteralString
- Sequel::LooserTypecasting
- Sequel::MSSQL
- Sequel::MSSQL::DatabaseMethods
- Sequel::MSSQL::DatasetMethods
- Sequel::MSSQL::EmulateLateralWithApply
- Sequel::Metaprogramming
- Sequel::Migration
- Sequel::MigrationAlterTableReverser
- Sequel::MigrationDSL
- Sequel::MigrationReverser
- Sequel::Migrator
- Sequel::Migrator::Error
- Sequel::Migrator::NotCurrentError
- Sequel::Mock
- Sequel::Mock::Connection
- Sequel::Mock::Database
- Sequel::Mock::Dataset
- Sequel::Model
- Sequel::Model::Associations
- Sequel::Model::Associations::AssociationDatasetMethods
- Sequel::Model::Associations::AssociationReflection
- Sequel::Model::Associations::ClassMethods
- Sequel::Model::Associations::DatasetMethods
- Sequel::Model::Associations::EagerGraphLoader
- Sequel::Model::Associations::InstanceMethods
- Sequel::Model::Associations::ManyToManyAssociationReflection
- Sequel::Model::Associations::ManyToOneAssociationReflection
- Sequel::Model::Associations::OneThroughOneAssociationReflection
- Sequel::Model::Associations::OneToManyAssociationReflection
- Sequel::Model::Associations::OneToOneAssociationReflection
- Sequel::Model::Associations::SingularAssociationReflection
- Sequel::Model::ClassMethods
- Sequel::Model::DatasetMethods
- Sequel::Model::DatasetModule
- Sequel::Model::Errors
- Sequel::Model::InstanceMethods
- Sequel::MySQL
- Sequel::MySQL::Database
- Sequel::MySQL::DatabaseMethods
- Sequel::MySQL::Dataset
- Sequel::MySQL::DatasetMethods
- Sequel::MySQL::PreparedStatements
- Sequel::MySQL::PreparedStatements::DatabaseMethods
- Sequel::MySQL::PreparedStatements::DatasetMethods
- Sequel::MySQL::PreparedStatements::DatasetMethods::CallableStatementMethods
- Sequel::MySQL::PreparedStatements::DatasetMethods::PreparedStatementMethods
- Sequel::MySQL::PreparedStatements::DatasetMethods::StoredProcedureMethods
- Sequel::Mysql2
- Sequel::Mysql2::Database
- Sequel::Mysql2::Dataset
- Sequel::NamedTimezones
- Sequel::NamedTimezones::DatabaseMethods
- Sequel::NoExistingObject
- Sequel::NoMatchingRow
- Sequel::NotNullConstraintViolation
- 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::Dataset::ArgumentMapper
- Sequel::Oracle::Dataset::BindArgumentMethods
- Sequel::Oracle::Dataset::PreparedStatementMethods
- Sequel::Oracle::DatasetMethods
- Sequel::Plugins
- Sequel::Plugins::ActiveModel
- Sequel::Plugins::ActiveModel::ClassMethods
- Sequel::Plugins::ActiveModel::Errors
- Sequel::Plugins::ActiveModel::InstanceMethods
- Sequel::Plugins::AfterInitialize
- Sequel::Plugins::AfterInitialize::ClassMethods
- Sequel::Plugins::AfterInitialize::InstanceMethods
- Sequel::Plugins::AssociationAutoreloading
- Sequel::Plugins::AssociationDependencies
- Sequel::Plugins::AssociationDependencies::ClassMethods
- Sequel::Plugins::AssociationDependencies::InstanceMethods
- Sequel::Plugins::AssociationPks
- Sequel::Plugins::AssociationPks::ClassMethods
- Sequel::Plugins::AssociationPks::InstanceMethods
- Sequel::Plugins::AssociationProxies
- Sequel::Plugins::AssociationProxies::AssociationProxy
- Sequel::Plugins::AssociationProxies::ClassMethods
- Sequel::Plugins::AutoValidations
- Sequel::Plugins::AutoValidations::ClassMethods
- Sequel::Plugins::AutoValidations::InstanceMethods
- Sequel::Plugins::BlacklistSecurity
- Sequel::Plugins::BlacklistSecurity::ClassMethods
- Sequel::Plugins::BlacklistSecurity::InstanceMethods
- Sequel::Plugins::BlacklistSecurity::InstanceMethods::ExceptionList
- 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::ConstraintValidations
- Sequel::Plugins::ConstraintValidations::ClassMethods
- Sequel::Plugins::ConstraintValidations::DatabaseMethods
- Sequel::Plugins::ConstraintValidations::InstanceMethods
- Sequel::Plugins::DatasetAssociations
- Sequel::Plugins::DatasetAssociations::ClassMethods
- Sequel::Plugins::DatasetAssociations::DatasetMethods
- Sequel::Plugins::DefaultsSetter
- Sequel::Plugins::DefaultsSetter::ClassMethods
- Sequel::Plugins::DefaultsSetter::InstanceMethods
- Sequel::Plugins::Dirty
- Sequel::Plugins::Dirty::InstanceMethods
- Sequel::Plugins::EagerEach
- Sequel::Plugins::EagerEach::DatasetMethods
- Sequel::Plugins::ErrorSplitter
- Sequel::Plugins::ErrorSplitter::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::InputTransformer
- Sequel::Plugins::InputTransformer::ClassMethods
- Sequel::Plugins::InputTransformer::InstanceMethods
- Sequel::Plugins::InstanceFilters
- Sequel::Plugins::InstanceFilters::Error
- Sequel::Plugins::InstanceFilters::InstanceMethods
- Sequel::Plugins::InstanceHooks
- Sequel::Plugins::InstanceHooks::InstanceMethods
- Sequel::Plugins::JsonSerializer
- Sequel::Plugins::JsonSerializer::ClassMethods
- Sequel::Plugins::JsonSerializer::DatasetMethods
- Sequel::Plugins::JsonSerializer::InstanceMethods
- Sequel::Plugins::JsonSerializer::Literal
- Sequel::Plugins::LazyAttributes
- Sequel::Plugins::LazyAttributes::ClassMethods
- Sequel::Plugins::LazyAttributes::InstanceMethods
- Sequel::Plugins::List
- Sequel::Plugins::List::ClassMethods
- Sequel::Plugins::List::InstanceMethods
- Sequel::Plugins::ManyThroughMany
- Sequel::Plugins::ManyThroughMany::ClassMethods
- Sequel::Plugins::ManyThroughMany::DatasetMethods
- Sequel::Plugins::ManyThroughMany::ManyThroughManyAssociationReflection
- Sequel::Plugins::ManyThroughMany::OneThroughManyAssociationReflection
- Sequel::Plugins::ManyToOnePkLookup
- Sequel::Plugins::MssqlOptimisticLocking
- Sequel::Plugins::MssqlOptimisticLocking::ClassMethods
- Sequel::Plugins::MssqlOptimisticLocking::InstanceMethods
- Sequel::Plugins::NestedAttributes
- Sequel::Plugins::NestedAttributes::ClassMethods
- Sequel::Plugins::NestedAttributes::InstanceMethods
- Sequel::Plugins::OptimisticLocking
- Sequel::Plugins::OptimisticLocking::ClassMethods
- Sequel::Plugins::OptimisticLocking::Error
- Sequel::Plugins::OptimisticLocking::InstanceMethods
- Sequel::Plugins::PgArrayAssociations
- Sequel::Plugins::PgArrayAssociations::ClassMethods
- Sequel::Plugins::PgArrayAssociations::DatasetMethods
- Sequel::Plugins::PgArrayAssociations::ManyToPgArrayAssociationReflection
- Sequel::Plugins::PgArrayAssociations::PgArrayToManyAssociationReflection
- Sequel::Plugins::PgRow
- Sequel::Plugins::PgRow::ClassMethods
- Sequel::Plugins::PgRow::DatabaseMethods
- Sequel::Plugins::PgRow::InstanceMethods
- Sequel::Plugins::PgTypecastOnLoad
- Sequel::Plugins::PgTypecastOnLoad::ClassMethods
- Sequel::Plugins::PgTypecastOnLoad::InstanceMethods
- Sequel::Plugins::PreparedStatements
- Sequel::Plugins::PreparedStatements::ClassMethods
- Sequel::Plugins::PreparedStatements::InstanceMethods
- Sequel::Plugins::PreparedStatementsAssociations
- Sequel::Plugins::PreparedStatementsAssociations::InstanceMethods
- Sequel::Plugins::PreparedStatementsSafe
- Sequel::Plugins::PreparedStatementsSafe::ClassMethods
- Sequel::Plugins::PreparedStatementsSafe::InstanceMethods
- Sequel::Plugins::PreparedStatementsWithPk
- Sequel::Plugins::PreparedStatementsWithPk::ClassMethods
- Sequel::Plugins::PreparedStatementsWithPk::DatasetMethods
- Sequel::Plugins::RcteTree
- Sequel::Plugins::Schema
- Sequel::Plugins::Schema::ClassMethods
- Sequel::Plugins::Scissors
- Sequel::Plugins::Scissors::ClassMethods
- Sequel::Plugins::Serialization
- Sequel::Plugins::Serialization::ClassMethods
- Sequel::Plugins::Serialization::InstanceMethods
- Sequel::Plugins::SerializationModificationDetection
- Sequel::Plugins::SerializationModificationDetection::InstanceMethods
- Sequel::Plugins::Sharding
- Sequel::Plugins::Sharding::ClassMethods
- Sequel::Plugins::Sharding::DatasetMethods
- Sequel::Plugins::Sharding::InstanceMethods
- Sequel::Plugins::SingleTableInheritance
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- Sequel::Plugins::SkipCreateRefresh
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- Sequel::Plugins::TacticalEagerLoading
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- Sequel::Plugins::Timestamps
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- Sequel::Plugins::Timestamps::InstanceMethods
- Sequel::Plugins::Touch
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- Sequel::Plugins::Tree
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- Sequel::Plugins::Tree::InstanceMethods
- Sequel::Plugins::Tree::SingleRoot
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- Sequel::Plugins::Tree::SingleRoot::InstanceMethods
- Sequel::Plugins::Tree::TreeMultipleRootError
- Sequel::Plugins::TypecastOnLoad
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- Sequel::Plugins::UnlimitedUpdate
- Sequel::Plugins::UnlimitedUpdate::InstanceMethods
- Sequel::Plugins::UpdateOrCreate
- Sequel::Plugins::UpdateOrCreate::ClassMethods
- Sequel::Plugins::UpdatePrimaryKey
- Sequel::Plugins::UpdatePrimaryKey::InstanceMethods
- Sequel::Plugins::ValidationClassMethods
- Sequel::Plugins::ValidationClassMethods::ClassMethods
- Sequel::Plugins::ValidationClassMethods::ClassMethods::Generator
- Sequel::Plugins::ValidationClassMethods::InstanceMethods
- Sequel::Plugins::ValidationHelpers
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- Sequel::Plugins::XmlSerializer
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- Sequel::Plugins::XmlSerializer::DatasetMethods
- Sequel::Plugins::XmlSerializer::InstanceMethods
- Sequel::PoolTimeout
- Sequel::Postgres
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- Sequel::Postgres::ArrayOp
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- Sequel::Postgres::CreateTableGenerator
- 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::Postgres::ExclusionConstraintViolation
- Sequel::Postgres::HStore
- Sequel::Postgres::HStore::DatabaseMethods
- Sequel::Postgres::HStore::Parser
- Sequel::Postgres::HStoreOp
- Sequel::Postgres::HStoreOpMethods
- Sequel::Postgres::InetDatabaseMethods
- Sequel::Postgres::InetDatasetMethods
- Sequel::Postgres::IntervalDatabaseMethods
- Sequel::Postgres::IntervalDatabaseMethods::Parser
- Sequel::Postgres::IntervalDatasetMethods
- Sequel::Postgres::JSONArray
- Sequel::Postgres::JSONArrayBase
- Sequel::Postgres::JSONBArray
- Sequel::Postgres::JSONBHash
- Sequel::Postgres::JSONBOp
- Sequel::Postgres::JSONBaseOp
- Sequel::Postgres::JSONDatabaseMethods
- Sequel::Postgres::JSONHash
- Sequel::Postgres::JSONHashBase
- Sequel::Postgres::JSONOp
- Sequel::Postgres::JSONOpMethods
- Sequel::Postgres::LooseCount
- Sequel::Postgres::PGArray
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- Sequel::Postgres::PGRange::DatasetMethods
- Sequel::Postgres::PGRange::Parser
- Sequel::Postgres::PGRow
- Sequel::Postgres::PGRow::ArrayRow
- Sequel::Postgres::PGRow::DatabaseMethods
- Sequel::Postgres::PGRow::HashRow
- Sequel::Postgres::PGRow::Parser
- Sequel::Postgres::PGRow::Splitter
- Sequel::Postgres::PGRowOp
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- Sequel::Qualifier
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- Sequel::SQL::Blob
- Sequel::SQL::BooleanConstant
- Sequel::SQL::BooleanExpression
- Sequel::SQL::BooleanMethods
- Sequel::SQL::Builders
- 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::DateAdd
- Sequel::SQL::DateAdd::DatasetMethods
- Sequel::SQL::DelayedEvaluation
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- Sequel::SQL::Identifier
- Sequel::SQL::InequalityMethods
- Sequel::SQL::JoinClause
- Sequel::SQL::JoinOnClause
- Sequel::SQL::JoinUsingClause
- Sequel::SQL::NegativeBooleanConstant
- Sequel::SQL::NumericExpression
- Sequel::SQL::NumericMethods
- Sequel::SQL::OperatorBuilders
- Sequel::SQL::OrderMethods
- Sequel::SQL::OrderedExpression
- Sequel::SQL::PlaceholderLiteralString
- Sequel::SQL::QualifiedIdentifier
- Sequel::SQL::QualifyingMethods
- Sequel::SQL::StringConcatenationMethods
- Sequel::SQL::StringExpression
- Sequel::SQL::StringMethods
- Sequel::SQL::Subscript
- Sequel::SQL::SubscriptMethods
- Sequel::SQL::ValueList
- Sequel::SQL::VirtualRow
- Sequel::SQL::Window
- Sequel::SQL::WindowFunction
- Sequel::SQL::Wrapper
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- Sequel::SqlAnywhere::Dataset
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- Sequel::SqlAnywhere::SQLAnywhereException
- Sequel::Swift
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- Sequel::Swift::MySQL
- Sequel::Swift::MySQL::DatabaseMethods
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- Sequel::Swift::Postgres
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- Sequel::Swift::SQLite
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- Sequel::Swift::SQLite::Dataset
- Sequel::ThreadLocalTimezones
- Sequel::ThreadedConnectionPool
- Sequel::ThreadedServerBlock
- Sequel::TimestampMigrator
- Sequel::Timezones
- Sequel::TinyTDS
- Sequel::TinyTDS::Database
- Sequel::TinyTDS::Dataset
- Sequel::TinyTDS::Dataset::ArgumentMapper
- Sequel::TinyTDS::Dataset::PreparedStatementMethods
- Sequel::ToDot
- Sequel::ToDot::DatasetMethods
- Sequel::UnbindDuplicate
- Sequel::Unbinder
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- String
- String::Inflections
- Array
- FalseClass
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- Numeric
- Object
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- Symbol
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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.

### Constants

OPTS

## 1 - 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.

EXTENSIONS

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

JOIN_METHODS

  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 Class Methods

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

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

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

    # File lib/sequel/dataset/query.rb, line 53
    def self.register_extension(ext, mod=nil, &block)
      if mod
        raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block
        if mod.is_a?(Module)
          block = proc{|ds| ds.extend(mod)}
          Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)}
        else
          block = mod
        end
      end
      Sequel.synchronize{EXTENSIONS[ext] = block}
    end

### Public Instance Methods

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

Alias for where.

    # File lib/sequel/dataset/query.rb, line 67
    def and(*cond, &block)
      where(*cond, &block)
    end

clone(opts = nil) 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. This method should generally not be called directly by user code.

    # File lib/sequel/dataset/query.rb, line 75
    def clone(opts = nil)
      c = super()
      if opts
        c.instance_variable_set(:@opts, @opts.merge(opts))
        c.instance_variable_set(:@columns, nil) if @columns && !opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)}
      else
        c.instance_variable_set(:@opts, @opts.dup)
      end
      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.

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

    # File lib/sequel/dataset/query.rb, line 95
    def distinct(*args)
      raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on?
      clone(:distinct => args)
    end

except(dataset, opts=OPTS) click to toggle source

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

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

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

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

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

    # File lib/sequel/dataset/query.rb, line 117
    def except(dataset, opts=OPTS)
      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#where. Note that if you have multiple filter conditions, this is not the same as a negation of all conditions.

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

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

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

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

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

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

    # File lib/sequel/dataset/query.rb, line 139
    def exclude_having(*cond, &block)
      _filter_or_exclude(true, :having, *cond, &block)
    end

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

Alias for exclude.

    # File lib/sequel/dataset/query.rb, line 144
    def exclude_where(*cond, &block)
      exclude(*cond, &block)
    end

extension(*exts) click to toggle source

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

    # File lib/sequel/dataset/query.rb, line 149
    def extension(*exts)
      clone.extension!(*exts)
    end

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

Alias for where.

    # File lib/sequel/dataset/query.rb, line 154
    def filter(*cond, &block)
      where(*cond, &block)
    end

for_update() click to toggle source

Returns a cloned dataset with a :update lock style.

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

    # File lib/sequel/dataset/query.rb, line 161
    def for_update
      lock_style(:update)
    end

from(*source, &block) click to toggle source

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

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

    # File lib/sequel/dataset/query.rb, line 174
    def from(*source, &block)
      virtual_row_columns(source, block)
      table_alias_num = 0
      ctes = nil
      source.map! do |s|
        case s
        when Dataset
          if hoist_cte?(s)
            ctes ||= []
            ctes += s.opts[:with]
            s = s.clone(:with=>nil)
          end
          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, table) : SQL::Identifier.new(table)
            SQL::AliasedExpression.new(s, aliaz.to_sym)
          else
            s
          end
        else
          s
        end
      end
      o = {:from=>source.empty? ? nil : source}
      o[:with] = (opts[:with] || []) + ctes if ctes
      o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
      clone(o)
    end

from_self(opts=OPTS) click to toggle source

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

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

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

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

    ds.from_self(:alias=>:foo, :column_aliases=>[:c1, :c2])
    # SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo(c1, c2)

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

grep(columns, patterns, opts=OPTS) click to toggle source

Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions (which are only supported on MySQL and PostgreSQL). Note that the total number of pattern matches will be Array(columns).length * Array(terms).length, which could cause performance issues.

Options (all are boolean):

:all_columns | All columns must be matched to any of the given patterns.
:all_patterns | All patterns must match at least one of the columns.
:case_insensitive | Use a case insensitive pattern match (the default is case sensitive if the database supports it).

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

Examples:

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

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

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

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

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

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

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

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

    DB[:items].group(:id) # SELECT * FROM items GROUP BY id
    DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name
    DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)

    # File lib/sequel/dataset/query.rb, line 281
    def group(*columns, &block)
      virtual_row_columns(columns, block)
      clone(:group => (columns.compact.empty? ? nil : columns))
    end

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

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

Examples:

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

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

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

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

    # File lib/sequel/dataset/query.rb, line 312
    def group_and_count(*columns, &block)
      select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT)
    end

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

Alias of group

    # File lib/sequel/dataset/query.rb, line 287
    def group_by(*columns, &block)
      group(*columns, &block)
    end

group_cube() click to toggle source

Adds the appropriate CUBE syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb, line 317
    def group_cube
      raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
      clone(:group_options=>:cube)
    end

group_rollup() click to toggle source

Adds the appropriate ROLLUP syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb, line 323
    def group_rollup
      raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
      clone(:group_options=>:rollup)
    end

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

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

    DB[:items].group(:sum).having(:sum=>10)
    # SELECT * FROM items GROUP BY sum HAVING (sum = 10)

    # File lib/sequel/dataset/query.rb, line 332
    def having(*cond, &block)
      _filter(:having, *cond, &block)
    end

intersect(dataset, opts=OPTS) click to toggle source

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

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

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

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

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

    # File lib/sequel/dataset/query.rb, line 353
    def intersect(dataset, opts=OPTS)
      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 WHERE and HAVING clauses. If there is neither a WHERE or HAVING clause, adds a WHERE clause that is always false.

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

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

    # File lib/sequel/dataset/query.rb, line 367
    def invert
      having, where = @opts.values_at(:having, :where)
      if having.nil? && where.nil?
        where(false)
      else
        o = {}
        o[:having] = SQL::BooleanExpression.invert(having) if having
        o[:where] = SQL::BooleanExpression.invert(where) if where
        clone(o)
      end
    end

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

Alias of `inner_join`

    # File lib/sequel/dataset/query.rb, line 380
    def join(*args, &block)
      inner_join(*args, &block)
    end

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

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

Takes the following arguments:

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

- table - Depends on type:

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

  - String, Symbol: table

- expr - specifies conditions, depends on type:

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

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

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

  - Everything else - pretty much the same as a using the argument in a call to where, so strings are considered literal, symbols specify boolean columns, and Sequel expressions can be used. Uses a JOIN with an ON clause.

- options - a hash of options, with any of the following keys:

  - :table_alias - the name of the table's alias when joining, necessary for joining to the same table more than once. No alias is used by default.

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

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

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

Examples:

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

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

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

    DB[:a].natural_join(:b).join_table(:inner, :c) do |ta, jta, js|
      (Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>DB.from(js.first.table).select(:g)}
    end
    # SELECT * FROM a NATURAL JOIN b INNER JOIN c
    #   ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))

    # File lib/sequel/dataset/query.rb, line 438
    def join_table(type, table, expr=nil, options=OPTS, &block)
      if hoist_cte?(table)
        s, ds = hoist_cte(table)
        return s.join_table(type, ds, expr, options, &block)
      end

      using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
      if using_join && !supports_join_using?
        h = {}
        expr.each{|e| h[e] = e}
        return join_table(type, table, h, options)
      end

      table_alias = options[:table_alias]
      last_alias = options[:implicit_qualifier]
      qualify_type = options[:qualify]

      if table.is_a?(SQL::AliasedExpression)
        table_expr = if table_alias
          SQL::AliasedExpression.new(table.expression, table_alias, table.columns)
        else
          table
        end
        table = table_expr.expression
        table_name = table_alias = table_expr.alias
      elsif table.is_a?(Dataset)
        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
        table_expr = SQL::AliasedExpression.new(table, table_alias)
      else
        table, implicit_table_alias = split_alias(table)
        table_alias ||= implicit_table_alias
        table_name = table_alias || table
        table_expr = table_alias ? SQL::AliasedExpression.new(table, table_alias) : table
      end

      join = if expr.nil? and !block
        SQL::JoinClause.new(type, table_expr)
      elsif using_join
        raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
        SQL::JoinUsingClause.new(expr, type, table_expr)
      else
        last_alias ||= @opts[:last_joined_table] || first_source_alias
        if Sequel.condition_specifier?(expr)
          expr = expr.collect do |k, v|
            qualify_type = default_join_table_qualification if qualify_type.nil?
            case qualify_type
            when false
              nil # Do no qualification
            when :deep
              k = Sequel::Qualifier.new(self, table_name).transform(k)
              v = Sequel::Qualifier.new(self, last_alias).transform(v)
            else
              k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
              v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
            end
            [k,v]
          end
          expr = SQL::BooleanExpression.from_value_pairs(expr)
        end
        if block
          expr2 = yield(table_name, last_alias, @opts[:join] || [])
          expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
        end
        SQL::JoinOnClause.new(expr, type, table_expr)
      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

lateral() click to toggle source

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

    DB.from(:a, DB[:b].where(:a__c=>:b__d).lateral)
    # SELECT * FROM a, LATERAL (SELECT * FROM b WHERE (a.c = b.d))

    # File lib/sequel/dataset/query.rb, line 526
    def lateral
      clone(:lateral=>true)
    end

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

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

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

    # File lib/sequel/dataset/query.rb, line 540
    def limit(l, o = (no_offset = true; nil))
      return from_self.limit(l, o) if @opts[:sql]

      if l.is_a?(Range)
        no_offset = false
        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

      ds = clone(:limit=>l)
      ds = ds.offset(o) unless no_offset
      ds
    end

lock_style(style) click to toggle source

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

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

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

    # File lib/sequel/dataset/query.rb, line 567
    def lock_style(style)
      clone(:lock => style)
    end

naked() click to toggle source

Returns a cloned dataset without a row_proc.

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

    # File lib/sequel/dataset/query.rb, line 577
    def naked
      ds = clone
      ds.row_proc = nil
      ds
    end

offset(o) click to toggle source

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

    DB[:items].offset(10) # SELECT * FROM items OFFSET 10

    # File lib/sequel/dataset/query.rb, line 588
    def offset(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
      clone(:offset => o)
    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.

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

    # File lib/sequel/dataset/query.rb, line 600
    def or(*cond, &block)
      cond = cond.first if cond.size == 1
      v = @opts[:where]
      if v.nil? || (cond.respond_to?(:empty?) && cond.empty? && !block)
        clone
      else
        clone(:where => SQL::BooleanExpression.new(:OR, v, filter_expr(cond, &block)))
      end
    end

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

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

    DB[:items].order(:name) # SELECT * FROM items ORDER BY name
    DB[:items].order(:a, :b) # SELECT * FROM items ORDER BY a, b
    DB[:items].order(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b
    DB[:items].order(:a + :b) # SELECT * FROM items ORDER BY (a + b)
    DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC
    DB[:items].order(Sequel.asc(:name, :nulls=>:last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST
    DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC
    DB[:items].order(nil) # SELECT * FROM items

    # File lib/sequel/dataset/query.rb, line 624
    def order(*columns, &block)
      virtual_row_columns(columns, 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 630
    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 635
    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.

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

    # File lib/sequel/dataset/query.rb, line 644
    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.

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

    # File lib/sequel/dataset/query.rb, line 654
    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 no table is given.

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

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

    # File lib/sequel/dataset/query.rb, line 666
    def qualify(table=first_source)
      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

returning(*values) click to toggle source

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

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

    # File lib/sequel/dataset/query.rb, line 685
    def returning(*values)
      clone(:returning=>values)
    end

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

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

    DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC
    DB[:items].reverse{foo(bar)} # SELECT * FROM items ORDER BY foo(bar) DESC
    DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC
    DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC

    # File lib/sequel/dataset/query.rb, line 696
    def reverse(*order, &block)
      virtual_row_columns(order, block)
      order(*invert_order(order.empty? ? @opts[:order] : order))
    end

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

Alias of `reverse`

    # File lib/sequel/dataset/query.rb, line 702
    def reverse_order(*order, &block)
      reverse(*order, &block)
    end

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

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

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

    # File lib/sequel/dataset/query.rb, line 713
    def select(*columns, &block)
      virtual_row_columns(columns, block)
      clone(:select => columns)
    end

select_all(*tables) click to toggle source

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

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

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

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

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

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

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

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

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

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

    DB[:items].select_group(:c___a){f(c2)}
    # SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)

    # File lib/sequel/dataset/query.rb, line 760
    def select_group(*columns, &block)
      virtual_row_columns(columns, block)
      select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
    end

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

Alias for select_append.

    # File lib/sequel/dataset/query.rb, line 766
    def select_more(*columns, &block)
      select_append(*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 (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.

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

    # File lib/sequel/dataset/query.rb, line 779
    def server(servr)
      clone(:server=>servr)
    end

unbind() click to toggle source

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

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

    # File lib/sequel/dataset/query.rb, line 793
    def unbind
      u = Unbinder.new
      ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join]))
      [ds, u.binds]
    end

unfiltered() click to toggle source

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

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

    # File lib/sequel/dataset/query.rb, line 803
    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.

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

    # File lib/sequel/dataset/query.rb, line 811
    def ungrouped
      clone(:group => nil, :having => nil)
    end

union(dataset, opts=OPTS) click to toggle source

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

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

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

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

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

    # File lib/sequel/dataset/query.rb, line 831
    def union(dataset, opts=OPTS)
      compound_clone(:union, dataset, opts)
    end

unlimited() click to toggle source

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

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

    # File lib/sequel/dataset/query.rb, line 838
    def unlimited
      clone(:limit=>nil, :offset=>nil)
    end

unordered() click to toggle source

Returns a copy of the dataset with no order.

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

    # File lib/sequel/dataset/query.rb, line 845
    def unordered
      order(nil)
    end

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

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

Accepts the following argument types:

- Hash - list of equality/inclusion expressions

- Array - depends:

  - If first member is a string, assumes the rest of the arguments are parameters and interpolates them into the string.

  - If all members are arrays of length two, treats the same way as a hash, except it allows for duplicate keys to be specified.

  - Otherwise, treats each argument as a separate condition.

- String - taken literally

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

- Sequel::SQL::BooleanExpression - an existing condition expression, probably created using the Sequel expression filter DSL.

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

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

Examples:

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

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

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

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

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

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

Multiple where calls can be chained for scoping:

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

See the "Dataset Filtering" guide for more examples and details.

    # File lib/sequel/dataset/query.rb, line 899
    def where(*cond, &block)
      _filter(:where, *cond, &block)
    end

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

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

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

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

    # File lib/sequel/dataset/query.rb, line 911
    def with(name, dataset, opts=OPTS)
      raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
      if hoist_cte?(dataset)
        s, ds = hoist_cte(dataset)
        s.with(name, ds, opts)
      else
        clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)])
      end
    end

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

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

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

    DB[:t].with_recursive(:t,
      DB[:i1].select(:id, :parent_id).where(:parent_id=>nil),
      DB[:i1].join(:t, :id=>:parent_id).select(:i1__id, :i1__parent_id),
      :args=>[:id, :parent_id])

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

    # File lib/sequel/dataset/query.rb, line 937
    def with_recursive(name, nonrecursive, recursive, opts=OPTS)
      raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
      if hoist_cte?(nonrecursive)
        s, ds = hoist_cte(nonrecursive)
        s.with_recursive(name, ds, recursive, opts)
      elsif hoist_cte?(recursive)
        s, ds = hoist_cte(recursive)
        s.with_recursive(name, nonrecursive, ds, opts)
      else
        clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))])
      end
    end

with_sql(sql, *args) click to toggle source

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

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

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

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

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

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

    # File lib/sequel/dataset/query.rb, line 962
    def with_sql(sql, *args)
      if sql.is_a?(Symbol)
        sql = send(sql, *args)
      else
        sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
      end
      clone(:sql=>sql)
    end

### Protected Instance Methods

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

Add the dataset to the list of compounds

    # File lib/sequel/dataset/query.rb, line 974
    def compound_clone(type, dataset, opts)
      if hoist_cte?(dataset)
        s, ds = hoist_cte(dataset)
        return s.compound_clone(type, ds, opts)
      end
      ds = compound_from_self.clone(:compounds=>Array(@opts[:compounds]).map{|x| x.dup} + [[type, dataset.compound_from_self, opts[:all]]])
      opts[:from_self] == false ? ds : ds.from_self(opts)
    end

options_overlap(opts) click to toggle source

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

    # File lib/sequel/dataset/query.rb, line 984
    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 an underlying table, such as:

    SELECT * FROM table
    SELECT table.* FROM table

    # File lib/sequel/dataset/query.rb, line 992
    def simple_select_all?
      o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)}
      if (f = o[:from]) && f.length == 1 && (f.first.is_a?(Symbol) || f.first.is_a?(SQL::AliasedExpression))
        case o.length
        when 1
          true
        when 2
          (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
        else
          false
        end
      else
        false
      end
    end

## 2 - 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

<<(arg) click to toggle source

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

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

    # File lib/sequel/dataset/actions.rb, line 22
    def <<(arg)
      insert(arg)
      self
    end

[](*conditions) click to toggle source

Returns the first record matching the conditions. Examples:

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

    # File lib/sequel/dataset/actions.rb, line 31
    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

all(&block) click to toggle source

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

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

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

    # File lib/sequel/dataset/actions.rb, line 44
    def all(&block)
      _all(block){|a| each{|r| a << r}}
    end

avg(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

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

    # File lib/sequel/dataset/actions.rb, line 55
    def avg(column=Sequel.virtual_row(&Proc.new))
      aggregate_dataset.get{avg(column).as(:avg)}
    end

columns() click to toggle source

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

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

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

    # File lib/sequel/dataset/actions.rb, line 68
    def columns
      return @columns if @columns
      ds = unfiltered.unordered.naked.clone(:distinct => nil, :limit => 1, :offset=>nil)
      ds.each{break}
      @columns = ds.instance_variable_get(:@columns)
      @columns || []
    end

columns!() click to toggle source

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

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

    # File lib/sequel/dataset/actions.rb, line 81
    def columns!
      @columns = nil
      columns
    end

count(arg=(no_arg=true), &block) click to toggle source

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

    DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1
    # => 3
    DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1
    # => 2
    DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1
    # => 1

    # File lib/sequel/dataset/actions.rb, line 97
    def count(arg=(no_arg=true), &block)
      if no_arg
        if block
          arg = Sequel.virtual_row(&block)
          aggregate_dataset.get{count(arg).as(:count)}
        else
          aggregate_dataset.get{count{}.*.as(:count)}.to_i
        end
      elsif block
        raise Error, 'cannot provide both argument and block to Dataset#count'
      else
        aggregate_dataset.get{count(arg).as(:count)}
      end
    end

delete(&block) click to toggle source

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

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

    # File lib/sequel/dataset/actions.rb, line 117
    def delete(&block)
      sql = delete_sql
      if uses_returning?(:delete)
        returning_fetch_rows(sql, &block)
      else
        execute_dui(sql)
      end
    end

each() click to toggle source

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

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

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

    # File lib/sequel/dataset/actions.rb, line 135
    def each
      if row_proc = @row_proc
        fetch_rows(select_sql){|r| yield row_proc.call(r)}
      else
        fetch_rows(select_sql){|r| yield r}
      end
      self
    end

empty?() click to toggle source

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

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

    # File lib/sequel/dataset/actions.rb, line 148
    def empty?
      get(Sequel::SQL::AliasedExpression.new(1, :one)).nil?
    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.

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

Examples:

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

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

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

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

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

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

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

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

    # File lib/sequel/dataset/actions.rb, line 187
    def first(*args, &block)
      ds = block ? filter(&block) : self

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

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

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

    # File lib/sequel/dataset/actions.rb, line 204
    def first!(*args, &block)
      first(*args, &block) || raise(Sequel::NoMatchingRow)
    end

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

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

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

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

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

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

    DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1
    # => [6, 'foo']

    # File lib/sequel/dataset/actions.rb, line 226
    def get(column=(no_arg=true; nil), &block)
      ds = naked
      if block
        raise(Error, ARG_BLOCK_ERROR_MSG) unless no_arg
        ds = ds.select(&block)
        column = ds.opts[:select]
        column = nil if column.is_a?(Array) && column.length < 2
      else
        ds = if column.is_a?(Array)
          ds.select(*column)
        else
          ds.select(auto_alias_expression(column))
        end
      end

      if column.is_a?(Array)
       if r = ds.single_record
         r.values_at(*hash_key_symbols(column))
       end
      else
        ds.single_value
      end
    end

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

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

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

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

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

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

Options:

:commit_every | Open a new transaction for every given number of records. For example, if you provide a value of 50, will commit after every 50 records.
:return | When the :value is :primary_key, returns an array of autoincremented primary key values for the rows inserted.
:server | Set the server/shard to use for the transaction and insert queries.
:slice | Same as :commit_every, :commit_every takes precedence.

    # File lib/sequel/dataset/actions.rb, line 275
    def import(columns, values, opts=OPTS)
      return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)

      return if values.empty?
      raise(Error, IMPORT_ERROR_MSG) if columns.empty?
      ds = opts[:server] ? server(opts[:server]) : self

      if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice))
        offset = 0
        rows = []
        while offset < values.length
          rows << ds._import(columns, values[offset, slice_size], opts)
          offset += slice_size
        end
        rows.flatten
      else
        ds._import(columns, values, opts)
      end
    end

insert(*values, &block) 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.

`insert` handles a number of different argument formats:

no arguments or single empty hash | Uses DEFAULT VALUES
single hash | Most common format, treats keys as columns an values as values
single array | Treats entries as values, with no columns
two arrays | Treats first array as columns, second array as values
single Dataset | Treats as an insert based on a selection from the dataset given, with no columns
array and dataset | Treats as an insert based on a selection from the dataset given, with the columns given by the array.

Examples:

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

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

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

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

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

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

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

    # File lib/sequel/dataset/actions.rb, line 330
    def insert(*values, &block)
      sql = insert_sql(*values)
      if uses_returning?(:insert)
        returning_fetch_rows(sql, &block)
      else
        execute_insert(sql)
      end
    end

interval(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

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

    # File lib/sequel/dataset/actions.rb, line 346
    def interval(column=Sequel.virtual_row(&Proc.new))
      aggregate_dataset.get{(max(column) - min(column)).as(:interval)}
    end

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

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

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

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

    # File lib/sequel/dataset/actions.rb, line 360
    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` otherwise. Raises an `Error` if both an argument and block are given.

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

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

You can also provide an array of column names:

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

    # File lib/sequel/dataset/actions.rb, line 379
    def map(column=nil, &block)
      if column
        raise(Error, ARG_BLOCK_ERROR_MSG) if block
        return naked.map(column) if row_proc
        if column.is_a?(Array)
          super(){|r| r.values_at(*column)}
        else
          super(){|r| r[column]}
        end
      else
        super(&block)
      end
    end

max(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

    DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1
    # => 10
    DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1
    # => 7

    # File lib/sequel/dataset/actions.rb, line 400
    def max(column=Sequel.virtual_row(&Proc.new))
      aggregate_dataset.get{max(column).as(:max)}
    end

min(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

    DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1
    # => 1
    DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1
    # => 0

    # File lib/sequel/dataset/actions.rb, line 411
    def min(column=Sequel.virtual_row(&Proc.new))
      aggregate_dataset.get{min(column).as(:min)}
    end

multi_insert(hashes, opts=OPTS) click to toggle source

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

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

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

This respects the same options as import.

    # File lib/sequel/dataset/actions.rb, line 427
    def multi_insert(hashes, opts=OPTS)
      return if hashes.empty?
      columns = hashes.first.keys
      import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
    end

paged_each(opts=OPTS) click to toggle source

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

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

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

Options:

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

:strategy

The strategy to use for paging of results. By default this is :offset, for using an approach with a limit and offset for every page. This can be set to :filter, which uses a limit and a filter that excludes rows from previous pages. In order for this strategy to work, you must be selecting the columns you are ordering by, and non of the columns can contain NULLs. Note that some Sequel adapters have optimized implementations that will use cursors or streaming regardless of the :strategy option used.

:filter_values

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

Examples:

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

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

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

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

    # File lib/sequel/dataset/actions.rb, line 484
    def paged_each(opts=OPTS)
      unless @opts[:order]
        raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
      end

      total_limit = @opts[:limit]
      offset = @opts[:offset]
      if server = @opts[:server]
        opts = opts.merge(:server=>server)
      end

      rows_per_fetch = opts[:rows_per_fetch] || 1000
      strategy = if offset || total_limit
        :offset
      else
        opts[:strategy] || :offset
      end

      db.transaction(opts) do
        case strategy
        when :filter
          filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}}
          base_ds = ds = limit(rows_per_fetch)
          while ds
            last_row = nil
            ds.each do |row|
              last_row = row
              yield row
            end
            ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row)
          end
        else
          offset ||= 0
          num_rows_yielded = rows_per_fetch
          total_rows = 0

          while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
            if total_limit && total_rows + rows_per_fetch > total_limit
              rows_per_fetch = total_limit - total_rows
            end

            num_rows_yielded = 0
            limit(rows_per_fetch, offset).each do |row|
              num_rows_yielded += 1
              total_rows += 1 if total_limit
              yield row
            end

            offset += rows_per_fetch
          end
        end
      end

      self
    end

range(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

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

    # File lib/sequel/dataset/actions.rb, line 547
    def range(column=Sequel.virtual_row(&Proc.new))
      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 columns given.

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

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

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

When using this method, you must be sure that each expression has an alias that Sequel can determine. Usually you can do this by calling the as method on the expression and providing an alias.

    # File lib/sequel/dataset/actions.rb, line 568
    def select_hash(key_column, value_column)
      _select_hash(:to_hash, key_column, value_column)
    end

select_hash_groups(key_column, value_column) click to toggle source

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

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

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

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

When using this method, you must be sure that each expression has an alias that Sequel can determine. Usually you can do this by calling the as method on the expression and providing an alias.

    # File lib/sequel/dataset/actions.rb, line 587
    def select_hash_groups(key_column, value_column)
      _select_hash(:to_hash_groups, key_column, 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. Raises an Error if called with both an argument and a block.

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

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

You can also provide an array of column names:

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

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine. Usually you can do this by calling the as method on the expression and providing an alias.

    # File lib/sequel/dataset/actions.rb, line 611
    def select_map(column=nil, &block)
      _select_map(column, false, &block)
    end

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

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

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

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

You can also provide an array of column names:

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

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine. Usually you can do this by calling the as method on the expression and providing an alias.

    # File lib/sequel/dataset/actions.rb, line 631
    def select_order_map(column=nil, &block)
      _select_map(column, true, &block)
    end

single_record() click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 638
    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. Users should generally use `get` instead of this method.

    # File lib/sequel/dataset/actions.rb, line 646
    def single_value
      if r = ungraphed.naked.single_record
        r.values.first
      end
    end

sum(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

    DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1
    # => 55
    DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1
    # => 10

    # File lib/sequel/dataset/actions.rb, line 659
    def sum(column=Sequel.virtual_row(&Proc.new))
      aggregate_dataset.get{sum(column).as(:sum)}
    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.

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

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

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

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

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

    # File lib/sequel/dataset/actions.rb, line 682
    def to_hash(key_column, value_column = nil)
      h = {}
      if value_column
        return naked.to_hash(key_column, value_column) if row_proc
        if value_column.is_a?(Array)
          if key_column.is_a?(Array)
            each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
          else
            each{|r| h[r[key_column]] = r.values_at(*value_column)}
          end
        else
          if key_column.is_a?(Array)
            each{|r| h[r.values_at(*key_column)] = r[value_column]}
          else
            each{|r| h[r[key_column]] = r[value_column]}
          end
        end
      elsif key_column.is_a?(Array)
        each{|r| h[r.values_at(*key_column)] = r}
      else
        each{|r| h[r[key_column]] = r}
      end
      h
    end

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

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

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

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

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

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

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

    # File lib/sequel/dataset/actions.rb, line 725
    def to_hash_groups(key_column, value_column = nil)
      h = {}
      if value_column
        return naked.to_hash_groups(key_column, value_column) if row_proc
        if value_column.is_a?(Array)
          if key_column.is_a?(Array)
            each{|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
          else
            each{|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
          end
        else
          if key_column.is_a?(Array)
            each{|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
          else
            each{|r| (h[r[key_column]] ||= []) << r[value_column]}
          end
        end
      elsif key_column.is_a?(Array)
        each{|r| (h[r.values_at(*key_column)] ||= []) << r}
      else
        each{|r| (h[r[key_column]] ||= []) << r}
      end
      h
    end

truncate() click to toggle source

Truncates the dataset. Returns nil.

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

    # File lib/sequel/dataset/actions.rb, line 754
    def truncate
      execute_ddl(truncate_sql)
    end

update(values=OPTS, &block) click to toggle source

Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent. `values` should a hash where the keys are columns to set and values are the values to which to set the columns.

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

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

    # File lib/sequel/dataset/actions.rb, line 768
    def update(values=OPTS, &block)
      sql = update_sql(values)
      if uses_returning?(:update)
        returning_fetch_rows(sql, &block)
      else
        execute_dui(sql)
      end
    end

with_sql_all(sql, &block) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 779
    def with_sql_all(sql, &block)
      _all(block){|a| with_sql_each(sql){|r| a << r}}
    end

with_sql_delete(sql) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 786
    def with_sql_delete(sql)
      execute_dui(sql)
    end

Also aliased as: with_sql_update
with_sql_each(sql) click to toggle source

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

This method should not be called on a shared dataset if the columns selected in the given SQL do not match the columns in the receiver.

    # File lib/sequel/dataset/actions.rb, line 795
    def with_sql_each(sql)
      if row_proc = @row_proc
        fetch_rows(sql){|r| yield row_proc.call(r)}
      else
        fetch_rows(sql){|r| yield r}
      end
      self
    end

with_sql_first(sql) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 806
    def with_sql_first(sql)
      with_sql_each(sql){|r| return r}
      nil
    end

with_sql_insert(sql) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 822
    def with_sql_insert(sql)
      execute_insert(sql)
    end

with_sql_single_value(sql) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 814
    def with_sql_single_value(sql)
      if r = with_sql_first(sql)
        r.values.first
      end
    end

with_sql_update(sql) click to toggle source
Alias for: with_sql_delete

### Protected Instance Methods

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

Internals of import. If primary key values are requested, use separate insert commands for each row. Otherwise, call multi_insert_sql and execute each statement it gives separately.

    # File lib/sequel/dataset/actions.rb, line 831
    def _import(columns, values, opts)
      trans_opts = opts.merge(:server=>@opts[:server])
      if opts[:return] == :primary_key
        @db.transaction(trans_opts){values.map{|v| insert(columns, v)}}
      else
        stmts = multi_insert_sql(columns, values)
        @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}}
      end
    end

_select_map_multiple(ret_cols) click to toggle source

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

    # File lib/sequel/dataset/actions.rb, line 842
    def _select_map_multiple(ret_cols)
      map{|r| r.values_at(*ret_cols)}
    end

_select_map_single() click to toggle source

Returns an array of the first value in each row.

    # File lib/sequel/dataset/actions.rb, line 847
    def _select_map_single
      map{|r| r.values.first}
    end

## 3 - 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

exists() click to toggle source

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

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

    # File lib/sequel/dataset/sql.rb, line 12
    def exists
      SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
    end

insert_sql(*values) click to toggle source

Returns an INSERT SQL query string. See `insert`.

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

    # File lib/sequel/dataset/sql.rb, line 20
    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
          values = []
          vals.each do |k,v|
            columns << k
            values << v
          end
        when Dataset, Array, LiteralString
          values = vals
        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

      if values.is_a?(Array) && values.empty? && !insert_supports_empty_values?
        columns = [columns().last]
        values = [DEFAULT]
      end
      clone(:columns=>columns, :values=>values).send(:_insert_sql)
    end

literal_append(sql, v) click to toggle source

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

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

    # File lib/sequel/dataset/sql.rb, line 58
    def literal_append(sql, v)
      case v
      when Symbol
        if skip_symbol_cache?
          literal_symbol_append(sql, v)
        else
          unless l = db.literal_symbol(v)
            l = ''
            literal_symbol_append(l, v)
            db.literal_symbol_set(v, l)
          end
          sql << l
        end
      when String
        case v
        when LiteralString
          sql << v
        when SQL::Blob
          literal_blob_append(sql, v)
        else
          literal_string_append(sql, v)
        end
      when Integer
        sql << literal_integer(v)
      when Hash
        literal_hash_append(sql, v)
      when SQL::Expression
        literal_expression_append(sql, v)
      when Float
        sql << literal_float(v)
      when BigDecimal
        sql << literal_big_decimal(v)
      when NilClass
        sql << literal_nil
      when TrueClass
        sql << literal_true
      when FalseClass
        sql << literal_false
      when Array
        literal_array_append(sql, v)
      when Time
        v.is_a?(SQLTime) ? literal_sqltime_append(sql, v) : literal_time_append(sql, v)
      when DateTime
        literal_datetime_append(sql, v)
      when Date
        sql << literal_date(v)
      when Dataset
        literal_dataset_append(sql, v)
      else
        literal_other_append(sql, 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 117
    def multi_insert_sql(columns, values)
      case multi_insert_sql_strategy
      when :values
        sql = LiteralString.new('VALUES ')
        expression_list_append(sql, values.map{|r| Array(r)})
        [insert_sql(columns, sql)]
      when :union
        c = false
        sql = LiteralString.new('')
        u = UNION_ALL_SELECT
        f = empty_from_sql
        values.each do |v|
          if c
            sql << u
          else
            sql << SELECT << SPACE
            c = true
          end
          expression_list_append(sql, v)
          sql << f if f
        end
        [insert_sql(columns, sql)]
      else
        values.map{|r| insert_sql(columns, r)}
      end
    end

sql() click to toggle source

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

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

truncate_sql() click to toggle source

Returns a TRUNCATE SQL query string. See `truncate`

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

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

update_sql(values = OPTS) click to toggle source

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

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

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

    # File lib/sequel/dataset/sql.rb, line 171
    def update_sql(values = OPTS)
      return static_sql(opts[:sql]) if opts[:sql]
      check_modification_allowed!
      clone(:values=>values).send(:_update_sql)
    end

## 4 - Methods that describe what the dataset supports ↑ top

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

### 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 21
    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 10
    def quote_identifiers?
      if defined?(@quote_identifiers)
        @quote_identifiers
      else
        @quote_identifiers = db.quote_identifiers?
      end
    end

recursive_cte_requires_column_aliases?() click to toggle source

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

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

requires_placeholder_type_specifiers?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 39
    def requires_placeholder_type_specifiers?
      false
    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 33
    def requires_sql_standard_datetimes?
      false
    end

supports_cte?(type=:select) click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 46
    def supports_cte?(type=:select)
      false
    end

supports_cte_in_subqueries?() click to toggle source

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

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

supports_derived_column_lists?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 60
    def supports_derived_column_lists?
      true
    end

supports_distinct_on?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 65
    def supports_distinct_on?
      false
    end

supports_group_cube?() click to toggle source

Whether the dataset supports CUBE with GROUP BY.

    # File lib/sequel/dataset/features.rb, line 70
    def supports_group_cube?
      false
    end

supports_group_rollup?() click to toggle source

Whether the dataset supports ROLLUP with GROUP BY.

    # File lib/sequel/dataset/features.rb, line 75
    def supports_group_rollup?
      false
    end

supports_insert_select?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 81
    def supports_insert_select?
      supports_returning?(:insert)
    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 86
    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 91
    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 96
    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 101
    def supports_join_using?
      true
    end

supports_lateral_subqueries?() click to toggle source

Whether the dataset supports LATERAL for subqueries in the FROM or JOIN clauses.

    # File lib/sequel/dataset/features.rb, line 106
    def supports_lateral_subqueries?
      false
    end

supports_limits_in_correlated_subqueries?() click to toggle source

Whether limits are supported in correlated subqueries. True by default.

    # File lib/sequel/dataset/features.rb, line 111
    def supports_limits_in_correlated_subqueries?
      true
    end

supports_modifying_joins?() click to toggle source

Whether modifying joined datasets is supported.

    # File lib/sequel/dataset/features.rb, line 116
    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 122
    def supports_multiple_column_in?
      true
    end

supports_offsets_in_correlated_subqueries?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 127
    def supports_offsets_in_correlated_subqueries?
      true
    end

supports_ordered_distinct_on?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 133
    def supports_ordered_distinct_on?
      supports_distinct_on?
    end

supports_regexp?() click to toggle source

Whether the dataset supports pattern matching by regular expressions.

    # File lib/sequel/dataset/features.rb, line 138
    def supports_regexp?
      false
    end

supports_replace?() click to toggle source

Whether the dataset supports REPLACE syntax, false by default.

    # File lib/sequel/dataset/features.rb, line 143
    def supports_replace?
      false
    end

supports_returning?(type) click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 149
    def supports_returning?(type)
      false
    end

supports_select_all_and_column?() click to toggle source

Whether the database supports SELECT *, column FROM table

    # File lib/sequel/dataset/features.rb, line 154
    def supports_select_all_and_column?
      true
    end

supports_timestamp_timezones?() click to toggle source

Whether the dataset supports timezones in literal timestamps

    # File lib/sequel/dataset/features.rb, line 159
    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 164
    def supports_timestamp_usecs?
      true
    end

supports_where_true?() click to toggle source

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

    # File lib/sequel/dataset/features.rb, line 175
    def supports_where_true?
      true
    end

supports_window_functions?() click to toggle source

Whether the dataset supports window functions.

    # File lib/sequel/dataset/features.rb, line 169
    def supports_window_functions?
      false
    end

## 5 - Methods related to dataset graphing ↑ top

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

### Public Instance Methods

add_graph_aliases(graph_aliases) click to toggle source

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

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

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

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

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

Arguments:

dataset | Can be a symbol (specifying a table), another dataset, or an SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.
join_conditions | Any condition(s) allowed by `join_table`.
block | A block that is passed to `join_table`.

Options:

:from_self_alias | The alias to use when the receiver is not a graphed dataset but it contains multiple FROM tables or a JOIN. In this case, the receiver is wrapped in a from_self before graphing, and this option determines the alias to use.
:implicit_qualifier | The qualifier of implicit conditions, see join_table.
:join_type | The type of join to use (passed to `join_table`). Defaults to :left_outer.
:qualify | The type of qualification to do, see join_table.
:select | An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about the join that makes it important to use `graph` instead of `join_table`.
:table_alias | The alias to use for the table. If not specified, doesn't alias the table. You will get an error if the alias (or table) name is used more than once.

    # File lib/sequel/dataset/graph.rb, line 49
    def graph(dataset, join_conditions = nil, options = OPTS, &block)
      # Allow the use of a dataset or symbol as the first argument
      # Find the table name/dataset based on the argument
      table_alias = options[:table_alias]
      table = dataset
      create_dataset = true

      case dataset
      when Symbol
        # let alias be the same as the table name (sans any optional schema)
        # unless alias explicitly given in the symbol using ___ notation
        table_alias ||= split_symbol(table).compact.last
      when Dataset
        if dataset.simple_select_all?
          table = dataset.opts[:from].first
          table_alias ||= table
        else
          table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
        end
        create_dataset = false
      when SQL::Identifier
        table_alias ||= table.value
      when SQL::QualifiedIdentifier
        table_alias ||= split_qualifiers(table).last
      when SQL::AliasedExpression
        return graph(table.expression, join_conditions, {:table_alias=>table.alias}.merge(options), &block)
      else
        raise Error, "The dataset argument should be a symbol or dataset"
      end
      table_alias = table_alias.to_sym

      if create_dataset
        dataset = db.from(table)
      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)

      table_alias_qualifier = qualifier_from_alias_symbol(table_alias, table)
      implicit_qualifier = options[:implicit_qualifier]
      ds = self

      # Use a from_self if this is already a joined table (or from_self specifically disabled for graphs)
      if (@opts[:graph_from_self] != false && !@opts[:graph] && (@opts[:from].length > 1 || @opts[:join]))
        implicit_qualifier = options[:from_self_alias] || first_source
        ds = ds.from_self(:alias=>implicit_qualifier)
      end

      # 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_qualifier, :implicit_qualifier=>implicit_qualifier, :qualify=>options[:qualify], &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
      if graph = opts[:graph]
        opts[:graph] = graph = graph.dup
        select = opts[:select].dup
        [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
      else
        qualifier = ds.first_source_alias
        master = alias_symbol(qualifier)
        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
          if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll)))
            select = select.each do |sel|
              column = case sel
              when Symbol
                _, c, a = split_symbol(sel)
                (a || c).to_sym
              when SQL::Identifier
                sel.value.to_sym
              when SQL::QualifiedIdentifier
                column = sel.column
                column = column.value if column.is_a?(SQL::Identifier)
                column.to_sym
              when SQL::AliasedExpression
                column = sel.alias
                column = column.value if column.is_a?(SQL::Identifier)
                column.to_sym
              else
                raise Error, "can't figure out alias to use for graphing for #{sel.inspect}"
              end
              column_aliases[column] = [master, column]
            end
            select = qualified_expression(select, qualifier)
          else
            select = columns.map do |column|
              column_aliases[column] = [master, column]
              SQL::QualifiedIdentifier.new(qualifier, column)
            end
          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
        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::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias_qualifier, column), column_alias)]
          else
            ident = SQL::QualifiedIdentifier.new(table_alias_qualifier, column)
            [column, ident]
          end
          column_aliases[col_alias] = [table_alias, column]
          select.push(identifier)
        end
      end
      add_columns ? ds.select(*select) : 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.

graph_aliases

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

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

    # File lib/sequel/dataset/graph.rb, line 225
    def set_graph_aliases(graph_aliases)
      columns, graph_aliases = graph_alias_columns(graph_aliases)
      ds = select(*columns)
      ds.opts[:graph_aliases] = graph_aliases
      ds
    end

ungraphed() click to toggle source

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

    # File lib/sequel/dataset/graph.rb, line 234
    def ungraphed
      clone(:graph=>nil, :graph_aliases=>nil)
    end

## 6 - 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[R]

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

opts[R]

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

### Public Class Methods

new(db) click to toggle source

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

    DB[:posts]

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

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

### Public Instance Methods

==(o) click to toggle source

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

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

current_datetime() click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 41
    def current_datetime
      Sequel.datetime_class.now
    end

dup() click to toggle source

Similar to clone, but returns an unfrozen clone if the receiver is frozen.

    # File lib/sequel/dataset/misc.rb, line 51
    def dup
      o = clone
      o.opts.delete(:frozen)
      o
    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 62
    def each_server
      db.servers.each{|s| yield server(s)}
    end

eql?(o) click to toggle source

Alias for ==

    # File lib/sequel/dataset/misc.rb, line 46
    def eql?(o)
      self == o
    end

escape_like(string) click to toggle source

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

    ds.escape_like("foo\\%_") # 'foo\\\%\_'

    # File lib/sequel/dataset/misc.rb, line 71
    def escape_like(string)
      string.gsub(/[\\%_]/){|m| "\\#{m}"}
    end

first_source() click to toggle source

Alias of `first_source_alias`

    # File lib/sequel/dataset/misc.rb, line 87
    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.

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

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

    # File lib/sequel/dataset/misc.rb, line 99
    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.alias
      when Symbol
        _, _, 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

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

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

    # File lib/sequel/dataset/misc.rb, line 124
    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

freeze() click to toggle source

Sets the frozen flag on the dataset, so you can't modify it. Returns the receiver.

    # File lib/sequel/dataset/misc.rb, line 76
    def freeze
      @opts[:frozen] = true
      self
    end

frozen?() click to toggle source

Whether the object is frozen.

    # File lib/sequel/dataset/misc.rb, line 82
    def frozen?
      @opts[:frozen]
    end

hash() click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 142
    def hash
      [db, opts, sql].hash
    end

identifier_input_method() click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 148
    def identifier_input_method
      if defined?(@identifier_input_method)
        @identifier_input_method
      else
        @identifier_input_method = db.identifier_input_method
      end
    end

identifier_output_method() click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 158
    def identifier_output_method
      if defined?(@identifier_output_method)
        @identifier_output_method
      else
        @identifier_output_method = db.identifier_output_method
      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 168
    def inspect
      "#<#{visible_class_name}: #{sql.inspect}>"
    end

row_number_column() click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 174
    def row_number_column
      :x_sequel_row_number_x
    end

split_alias(c) click to toggle source

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

    # File lib/sequel/dataset/misc.rb, line 181
    def split_alias(c)
      case c
      when Symbol
        c_table, column, aliaz = split_symbol(c)
        [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
      when SQL::AliasedExpression
        [c.expression, c.alias]
      when SQL::JoinClause
        [c.table, c.table_alias]
      else
        [c, nil]
      end
    end

unused_table_alias(table_alias, used_aliases = []) click to toggle source

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

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

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

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

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

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

    # File lib/sequel/dataset/misc.rb, line 217
    def unused_table_alias(table_alias, used_aliases = [])
      table_alias = alias_symbol(table_alias)
      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

## 7 - 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

row_proc[R]

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

### Public Class Methods

def_mutation_method(*meths) 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.

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

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

### Public Instance Methods

extension!(*exts) click to toggle source

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

    # File lib/sequel/dataset/mutation.rb, line 38
    def extension!(*exts)
      raise_if_frozen!
      Sequel.extension(*exts)
      exts.each do |ext|
        if pr = Sequel.synchronize{EXTENSIONS[ext]}
          pr.call(self)
        else
          raise(Error, "Extension #{ext} does not have specific support handling individual datasets")
        end
      end
      self
    end

from_self!(*args, &block) click to toggle source

Avoid self-referential dataset by cloning.

    # File lib/sequel/dataset/mutation.rb, line 52
    def from_self!(*args, &block)
      raise_if_frozen!
      @opts = clone.from_self(*args, &block).opts
      self
    end

identifier_input_method=(v) click to toggle source

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

    # File lib/sequel/dataset/mutation.rb, line 59
    def identifier_input_method=(v)
      raise_if_frozen!
      skip_symbol_cache!
      @identifier_input_method = v
    end

identifier_output_method=(v) click to toggle source

Set the method to call on identifiers coming the database for this dataset

    # File lib/sequel/dataset/mutation.rb, line 66
    def identifier_output_method=(v)
      raise_if_frozen!
      @identifier_output_method = v
    end

naked!() click to toggle source

Remove the row_proc from the current dataset.

    # File lib/sequel/dataset/mutation.rb, line 72
    def naked!
      raise_if_frozen!
      self.row_proc = nil
      self
    end

quote_identifiers=(v) click to toggle source

Set whether to quote identifiers for this dataset

    # File lib/sequel/dataset/mutation.rb, line 79
    def quote_identifiers=(v)
      raise_if_frozen!
      skip_symbol_cache!
      @quote_identifiers = v
    end

row_proc=(v) click to toggle source

Override the row_proc for this dataset

    # File lib/sequel/dataset/mutation.rb, line 86
    def row_proc=(v)
      raise_if_frozen!
      @row_proc = v
    end

## 8 - 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.

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

    # File lib/sequel/dataset/prepared_statements.rb, line 223
    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, :first, :insert, :insert_select, :update, or :delete), run the sql with the bind variables specified in the hash. `values` is a hash passed to insert or update (if one of those types is used), which may contain placeholders.

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

    # File lib/sequel/dataset/prepared_statements.rb, line 234
    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. Takes a type similar to call, and the `name` symbol of the prepared statement. While `name` defaults to `nil`, it should always be provided as a symbol for the name of the prepared statement, as some databases require that prepared statements have names.

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

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

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

    DB.call(:select_by_name, :name=>'Blah') # Same thing

    # File lib/sequel/dataset/prepared_statements.rb, line 256
    def prepare(type, name=nil, *values)
      ps = to_prepared_statement(type, values)
      db.set_prepared_statement(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 266
    def to_prepared_statement(type, values=nil)
      ps = bind
      ps.extend(PreparedStatementMethods)
      ps.orig_dataset = self
      ps.prepared_type = type
      ps.prepared_modify_values = values
      ps
    end

## 9 - Internal Methods relating to SQL Creation ↑ top

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

### Constants

ALL
AND_SEPARATOR
APOS
APOS_RE
ARRAY_EMPTY
AS
ASC
BACKSLASH
BITCOMP_CLOSE
BITCOMP_OPEN
BITWISE_METHOD_MAP
BOOL_FALSE
BOOL_TRUE
BRACKET_CLOSE
BRACKET_OPEN
CASE_ELSE
CASE_END
CASE_OPEN
CASE_THEN
CASE_WHEN
CAST_OPEN
COLON
COLUMN_REF_RE1
COLUMN_REF_RE2
COLUMN_REF_RE3
COMMA
COMMA_SEPARATOR
CONDITION_FALSE
CONDITION_TRUE
COUNT_FROM_SELF_OPTS
COUNT_OF_ALL_AS_COUNT
DATASET_ALIAS_BASE_NAME
DEFAULT
DEFAULT_VALUES
DELETE
DESC
DISTINCT
DOT
DOUBLE_APOS
DOUBLE_QUOTE
EMULATED_FUNCTION_MAP

  Map of emulated function names to native function names.

EQUAL
ESCAPE
EXISTS
EXTRACT
FILTER
FORMAT_DATE
FORMAT_DATE_STANDARD
FORMAT_OFFSET
FORMAT_TIMESTAMP_RE
FORMAT_TIMESTAMP_USEC
FORMAT_USEC
FOR_UPDATE
FRAME_ALL
FRAME_ROWS
FROM
FUNCTION_DISTINCT
GROUP_BY
HAVING
INSERT
INTO
IS_LITERALS
IS_OPERATORS
LATERAL
LIKE_OPERATORS
LIMIT
NOT_SPACE
NULL
NULLS_FIRST
NULLS_LAST
N_ARITY_OPERATORS
OFFSET
ON
ON_PAREN
ORDER_BY
ORDER_BY_NS
OVER
PAREN_CLOSE
PAREN_OPEN
PAREN_SPACE_OPEN
PARTITION_BY
QUALIFY_KEYS
QUESTION_MARK
QUESTION_MARK_RE
QUOTE
QUOTE_RE
REGEXP_OPERATORS
RETURNING
SELECT
SET
SPACE
SPACE_WITH
SQL_WITH
STANDARD_TIMESTAMP_FORMAT
TILDE
TIMESTAMP_FORMAT
TWO_ARITY_OPERATORS
UNDERSCORE
UNION_ALL_SELECT
UPDATE
USING
V190
VALUES
WHERE
WILDCARD
WITHIN_GROUP
WITH_ORDINALITY

### 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 184
    def self.clause_methods(type, clauses)
      clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze
    end

def_sql_method(mod, type, clauses) click to toggle source

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

Arguments:

mod | Module in which to define method
type | Type of SQL literalization method to create, either :select, :insert, :update, or :delete
clauses | array of clauses that make up the SQL query for the type. This can either be a single array of symbols/strings, or it can be an array of pairs, with the first element in each pair being an if/elsif/else code fragment, and the second element in each pair being an array of symbol/strings for the appropriate branch.

    # File lib/sequel/dataset/sql.rb, line 198
    def self.def_sql_method(mod, type, clauses)
      priv = type == :update || type == :insert

      lines = []
      lines << 'private' if priv
      lines << "def #{'_' if priv}#{type}_sql"
      lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv
      lines << 'check_modification_allowed!' if type == :delete
      lines << 'sql = @opts[:append_sql] || sql_string_origin'

      if clauses.all?{|c| c.is_a?(Array)}
        clauses.each do |i, cs|
          lines << i
          lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"})
        end
        lines << 'end'
      else
        lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"})
      end

      lines << 'sql'
      lines << 'end'

      mod.class_eval lines.join("\n"), __FILE__, __LINE__
    end

### Public Instance Methods

aliased_expression_sql_append(sql, ae) click to toggle source

Append literalization of aliased expression to SQL string.

    # File lib/sequel/dataset/sql.rb, line 350
    def aliased_expression_sql_append(sql, ae)
      literal_append(sql, ae.expression)
      as_sql_append(sql, ae.alias, ae.columns)
    end

array_sql_append(sql, a) click to toggle source

Append literalization of array to SQL string.

    # File lib/sequel/dataset/sql.rb, line 356
    def array_sql_append(sql, a)
      if a.empty?
        sql << ARRAY_EMPTY
      else
        sql << PAREN_OPEN
        expression_list_append(sql, a)
        sql << PAREN_CLOSE
      end
    end

boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb, line 367
    def boolean_constant_sql_append(sql, constant)
      if (constant == true || constant == false) && !supports_where_true?
        sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE)
      else
        literal_append(sql, constant)
      end
    end

case_expression_sql_append(sql, ce) click to toggle source

Append literalization of case expression to SQL string.

    # File lib/sequel/dataset/sql.rb, line 376
    def case_expression_sql_append(sql, ce)
      sql << CASE_OPEN
      if ce.expression?
        sql << SPACE
        literal_append(sql, ce.expression)
      end
      w = CASE_WHEN
      t = CASE_THEN
      ce.conditions.each do |c,r|
        sql << w
        literal_append(sql, c)
        sql << t
        literal_append(sql, r)
      end
      sql << CASE_ELSE
      literal_append(sql, ce.default)
      sql << CASE_END
    end

cast_sql_append(sql, expr, type) click to toggle source

Append literalization of cast expression to SQL string.

    # File lib/sequel/dataset/sql.rb, line 396
    def cast_sql_append(sql, expr, type)
      sql << CAST_OPEN
      literal_append(sql, expr)
      sql << AS << db.cast_type_literal(type).to_s
      sql << PAREN_CLOSE
    end

column_all_sql_append(sql, ca) click to toggle source

Append literalization of column all selection to SQL string.

    # File lib/sequel/dataset/sql.rb, line 404
    def column_all_sql_append(sql, ca)
      qualified_identifier_sql_append(sql, ca.table, WILDCARD)
    end

complex_expression_sql_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string.

    # File lib/sequel/dataset/sql.rb, line 409
    def complex_expression_sql_append(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 val = IS_LITERALS[r]
          sql << PAREN_OPEN
          literal_append(sql, args.at(0))
          sql << SPACE << op.to_s << SPACE
          sql << val << PAREN_CLOSE
        elsif op == :IS
          complex_expression_sql_append(sql, :"=", args)
        else
          complex_expression_sql_append(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)
        if vals.is_a?(Array)
          val_array = true
          empty_val_array = vals == []
        end
        if empty_val_array
          literal_append(sql, empty_array_value(op, cols))
        elsif col_array
          if !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_append(sql, op == :IN ? expr : ~expr)
            else
              old_vals = vals
              vals = vals.naked if vals.is_a?(Sequel::Dataset)
              vals = vals.to_a
              val_cols = old_vals.columns
              complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
            end
          else
            # If the columns and values are both arrays, use array_sql instead of
            # literal so that if values is an array of two element arrays, it
            # will be treated as a value list instead of a condition specifier.
            sql << PAREN_OPEN
            literal_append(sql, cols)
            sql << SPACE << op.to_s << SPACE
            if val_array
              array_sql_append(sql, vals)
            else
              literal_append(sql, vals)
            end
            sql << PAREN_CLOSE
          end
        else
          sql << PAREN_OPEN
          literal_append(sql, cols)
          sql << SPACE << op.to_s << SPACE
          literal_append(sql, vals)
          sql << PAREN_CLOSE
        end
      when :LIKE, :'NOT LIKE'
        sql << PAREN_OPEN
        literal_append(sql, args.at(0))
        sql << SPACE << op.to_s << SPACE
        literal_append(sql, args.at(1))
        sql << ESCAPE
        literal_append(sql, BACKSLASH)
        sql << PAREN_CLOSE
      when :ILIKE, :'NOT ILIKE'
        complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : :"NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)})
      when *TWO_ARITY_OPERATORS
        if REGEXP_OPERATORS.include?(op) && !supports_regexp?
          raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}"
        end
        sql << PAREN_OPEN
        literal_append(sql, args.at(0))
        sql << SPACE << op.to_s << SPACE
        literal_append(sql, args.at(1))
        sql << PAREN_CLOSE
      when *N_ARITY_OPERATORS
        sql << PAREN_OPEN
        c = false
        op_str = " #{op} "
        args.each do |a|
          sql << op_str if c
          literal_append(sql, a)
          c ||= true
        end
        sql << PAREN_CLOSE
      when :NOT
        sql << NOT_SPACE
        literal_append(sql, args.at(0))
      when :NOOP
        literal_append(sql, args.at(0))
      when :'B~'
        sql << TILDE
        literal_append(sql, args.at(0))
      when :extract
        sql << EXTRACT << args.at(0).to_s << FROM
        literal_append(sql, args.at(1))
        sql << PAREN_CLOSE
      else
        raise(InvalidOperation, "invalid operator #{op}")
      end
    end

constant_sql_append(sql, constant) click to toggle source

Append literalization of constant to SQL string.

    # File lib/sequel/dataset/sql.rb, line 514
    def constant_sql_append(sql, constant)
      sql << constant.to_s
    end

delayed_evaluation_sql_append(sql, callable) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 520
    def delayed_evaluation_sql_append(sql, callable)
      if recorder = @opts[:placeholder_literalizer]
        recorder.use(sql, callable, nil)
      else
        literal_append(sql, callable.call)
      end
    end

emulated_function_sql_append(sql, f) click to toggle source

REMOVE411

    # File lib/sequel/dataset/sql.rb, line 529
    def emulated_function_sql_append(sql, f)
      _function_sql_append(sql, native_function_name(f.f), f.args)
    end

function_sql_append(sql, f) click to toggle source

Append literalization of function call to SQL string.

    # File lib/sequel/dataset/sql.rb, line 534
    def function_sql_append(sql, f)
      name = f.name
      opts = f.opts

      if opts[:emulate]
        if emulate_function?(name)
          emulate_function_sql_append(sql, f)
          return
        end

        name = native_function_name(name)
      end

      sql << LATERAL if opts[:lateral]

      case name
      when SQL::Identifier
        if supports_quoted_function_names? && opts[:quoted] != false
          literal_append(sql, name)
        else
          sql << name.value.to_s
        end
      when SQL::QualifiedIdentifier
        if supports_quoted_function_names? && opts[:quoted] != false
          literal_append(sql, name)
        else
          sql << split_qualifiers(name).join(DOT)
        end
      else
        if supports_quoted_function_names? && opts[:quoted]
          quote_identifier_append(sql, name)
        else
          sql << name.to_s
        end
      end

      sql << PAREN_OPEN
      if opts[:*]
        sql << WILDCARD
      else
        sql << FUNCTION_DISTINCT if opts[:distinct]
        expression_list_append(sql, f.args)
      end
      sql << PAREN_CLOSE

      if group = opts[:within_group]
        sql << WITHIN_GROUP
        expression_list_append(sql, group)
        sql << PAREN_CLOSE
      end

      if filter = opts[:filter]
        sql << FILTER
        literal_append(sql, filter_expr(filter, &opts[:filter_block]))
        sql << PAREN_CLOSE
      end

      if window = opts[:over]
        sql << OVER
        window_sql_append(sql, window.opts)
      end

      if opts[:with_ordinality]
        sql << WITH_ORDINALITY
      end
    end

join_clause_sql_append(sql, jc) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 602
    def join_clause_sql_append(sql, jc)
      table = jc.table
      table_alias = jc.table_alias
      table_alias = nil if table == table_alias && !jc.column_aliases
      sql << SPACE << join_type_sql(jc.join_type) << SPACE
      identifier_append(sql, table)
      as_sql_append(sql, table_alias, jc.column_aliases) if table_alias
    end

join_on_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN ON clause to SQL string.

    # File lib/sequel/dataset/sql.rb, line 612
    def join_on_clause_sql_append(sql, jc)
      join_clause_sql_append(sql, jc)
      sql << ON
      literal_append(sql, filter_expr(jc.on))
    end

join_using_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN USING clause to SQL string.

    # File lib/sequel/dataset/sql.rb, line 619
    def join_using_clause_sql_append(sql, jc)
      join_clause_sql_append(sql, jc)
      sql << USING
      column_list_append(sql, jc.using)
      sql << PAREN_CLOSE
    end

negative_boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of negative boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb, line 627
    def negative_boolean_constant_sql_append(sql, constant)
      sql << NOT_SPACE
      boolean_constant_sql_append(sql, constant)
    end

ordered_expression_sql_append(sql, oe) click to toggle source

Append literalization of ordered expression to SQL string.

    # File lib/sequel/dataset/sql.rb, line 633
    def ordered_expression_sql_append(sql, oe)
      literal_append(sql, oe.expression)
      sql << (oe.descending ? DESC : ASC)
      case oe.nulls
      when :first
        sql << NULLS_FIRST
      when :last
        sql << NULLS_LAST
      end
    end

placeholder_literal_string_sql_append(sql, pls) click to toggle source

Append literalization of placeholder literal string to SQL string.

    # File lib/sequel/dataset/sql.rb, line 645
    def placeholder_literal_string_sql_append(sql, pls)
      args = pls.args
      str = pls.str
      sql << PAREN_OPEN if pls.parens
      if args.is_a?(Hash)
        if args.empty?
          sql << str
        else
          re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
          loop do
            previous, q, str = str.partition(re)
            sql << previous
            literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
            break if str.empty?
          end
        end
      elsif str.is_a?(Array)
        len = args.length
        str.each_with_index do |s, i|
          sql << s
          literal_append(sql, args[i]) unless i == len
        end
        unless str.length == args.length || str.length == args.length + 1
          raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
        end
      else
        i = -1
        match_len = args.length - 1
        loop do
          previous, q, str = str.partition(QUESTION_MARK)
          sql << previous
          literal_append(sql, args.at(i+=1)) unless q.empty?
          if str.empty?
            unless i == match_len
              raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder array"
            end
            break
          end
        end
      end
      sql << PAREN_CLOSE if pls.parens
    end

qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 691
    def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
      identifier_append(sql, table)
      sql << DOT
      identifier_append(sql, column)
    end

quote_identifier_append(sql, name) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 701
    def quote_identifier_append(sql, name)
      if name.is_a?(LiteralString)
        sql << name
      else
        name = name.value if name.is_a?(SQL::Identifier)
        name = input_identifier(name)
        if quote_identifiers?
          quoted_identifier_append(sql, name)
        else
          sql << name
        end
      end
    end

quote_schema_table_append(sql, table) click to toggle source

Append literalization of identifier or unqualified identifier to SQL string.

    # File lib/sequel/dataset/sql.rb, line 716
    def quote_schema_table_append(sql, table)
      schema, table = schema_and_table(table)
      if schema
        quote_identifier_append(sql, schema)
        sql << DOT
      end
      quote_identifier_append(sql, table)
    end

quoted_identifier_append(sql, name) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 729
    def quoted_identifier_append(sql, name)
      sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE
    end

schema_and_table(table_name, sch=nil) click to toggle source

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

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

    # File lib/sequel/dataset/sql.rb, line 740
    def schema_and_table(table_name, sch=nil)
      sch = sch.to_s if sch
      case table_name
      when Symbol
        s, t, _ = split_symbol(table_name)
        [s||sch, t]
      when SQL::QualifiedIdentifier
        [table_name.table.to_s, table_name.column.to_s]
      when SQL::Identifier
        [sch, table_name.value.to_s]
      when String
        [sch, table_name]
      else
        raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
      end
    end

split_qualifiers(table_name, *args) click to toggle source

Splits table_name into an array of strings.

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

    # File lib/sequel/dataset/sql.rb, line 763
    def split_qualifiers(table_name, *args)
      case table_name
      when SQL::QualifiedIdentifier
        split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
      else
        sch, table = schema_and_table(table_name, *args)
        sch ? [sch, table] : [table]
      end
    end

subscript_sql_append(sql, s) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 774
    def subscript_sql_append(sql, s)
      literal_append(sql, s.f)
      sql << BRACKET_OPEN
      if s.sub.length == 1 && (range = s.sub.first).is_a?(Range)
        literal_append(sql, range.begin)
        sql << COLON
        e = range.end
        e -= 1 if range.exclude_end? && e.is_a?(Integer)
        literal_append(sql, e)
      else
        expression_list_append(sql, s.sub)
      end
      sql << BRACKET_CLOSE
    end

window_function_sql_append(sql, function, window) click to toggle source

REMOVE411

    # File lib/sequel/dataset/sql.rb, line 831
    def window_function_sql_append(sql, function, window)
      Deprecation.deprecate("Dataset#window_function_sql_append", "Please use Sequel::SQL::Function.new(name, *args).over(...) to create an SQL window function")
      literal_append(sql, function)
      sql << OVER
      literal_append(sql, window)
    end

window_sql_append(sql, opts) click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 790
    def window_sql_append(sql, opts)
      raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
      sql << PAREN_OPEN
      window, part, order, frame = opts.values_at(:window, :partition, :order, :frame)
      space = false
      space_s = SPACE
      if window
        literal_append(sql, window)
        space = true
      end
      if part
        sql << space_s if space
        sql << PARTITION_BY
        expression_list_append(sql, Array(part))
        space = true
      end
      if order
        sql << space_s if space
        sql << ORDER_BY_NS
        expression_list_append(sql, Array(order))
        space = true
      end
      case frame
        when nil
          # nothing
        when :all
          sql << space_s if space
          sql << FRAME_ALL
        when :rows
          sql << space_s if space
          sql << FRAME_ROWS
        when String
          sql << space_s if space
          sql << frame
        else
          raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil"
      end
      sql << PAREN_CLOSE
    end

### Protected Instance Methods

compound_from_self() click to toggle source

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

    # File lib/sequel/dataset/sql.rb, line 842
    def compound_from_self
      (@opts[:limit] || @opts[:order]) ? from_self : self
    end

[Validate]

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