Class | Sequel::Database
In: | lib/sequel/database/misc.rb lib/sequel/database/dataset_defaults.rb lib/sequel/database/logging.rb lib/sequel/database/dataset.rb lib/sequel/database/schema_methods.rb lib/sequel/database/query.rb lib/sequel/database/connecting.rb lib/sequel/database.rb lib/sequel/extensions/query.rb lib/sequel/extensions/schema_dumper.rb lib/sequel/extensions/schema_caching.rb lib/sequel/adapters/jdbc.rb lib/sequel/adapters/do.rb lib/sequel/adapters/mysql.rb lib/sequel/adapters/sqlite.rb lib/sequel/adapters/swift.rb
Parent: | Object

Database class for SQLite databases used with Sequel and the ruby-sqlite3 driver.

### Contents

- 7 - Miscellaneous methods
- 5 - Methods that set defaults for created datasets
- 6 - Methods relating to logging
- 3 - Methods that create datasets
- 2 - Methods that modify the database schema
- 1 - Methods that execute queries and/or return results
- 4 - Methods relating to adapters, connecting, disconnecting, and sharding

### Methods

<< [] adapter_class adapter_scheme adapter_scheme add_column add_index add_servers after_commit after_rollback alter_table alter_table_generator call call_sproc cast_type_literal connect connect connect connect connect connect connect convert_invalid_date_time= convert_tinyint_to_bool= create_join_table create_or_replace_view create_table create_table! create_table? create_table_generator create_view database_type dataset dataset_class= disconnect drop_column drop_index drop_join_table drop_table drop_table? drop_view dump_foreign_key_migration dump_indexes_migration dump_schema_cache dump_schema_cache? dump_schema_migration dump_table_schema each_server execute execute execute execute execute execute_ddl execute_ddl execute_ddl execute_dui execute_dui execute_dui execute_dui execute_dui execute_dui execute_insert execute_insert execute_insert execute_insert execute_insert execute_insert extend_datasets extension fetch foreign_key_list from from_application_timestamp get global_index_namespace? identifier_input_method identifier_input_method identifier_input_method= identifier_input_method= identifier_output_method identifier_output_method identifier_output_method= identifier_output_method= in_transaction? indexes indexes inspect jndi? literal load_schema_cache load_schema_cache? log_exception log_info log_yield logger= new new new new new new prepared_statement query quote_identifiers= quote_identifiers= quote_identifiers? register_extension remove_servers rename_column rename_table run schema select serial_primary_key_options server_version servers set_column_default set_column_type set_prepared_statement single_threaded= single_threaded? subadapter supports_create_table_if_not_exists? supports_drop_table_if_exists? supports_prepared_transactions? supports_savepoints? supports_savepoints_in_prepared_transactions? supports_transaction_isolation_levels? supports_transactional_ddl? synchronize synchronize table_exists? tables tables test_connection timezone to_application_timestamp to_application_timestamp transaction typecast_value uri uri uri url views views

### Included Modules

Metaprogramming Sequel::MySQL::DatabaseMethods Sequel::MySQL::PreparedStatements::DatabaseMethods ::Sequel::SQLite::DatabaseMethods

## 7 - Miscellaneous methods

These methods don‘t fit neatly into another category.

### Constants

EXTENSIONS | = | {} |  | Hash of extension name symbols to callable objects to load the extension into the Database object (usually by extending it with a module defined in the extension).
LEADING_ZERO_RE | = | /\A0+(\d)/.freeze |  | Used for checking/removing leading zeroes from strings so they don‘t get interpreted as octal.
LEADING_ZERO_REP | = | "\\1".freeze |  | Replacement string when replacing leading zeroes.

### Attributes

opts | [R] | The options hash for this database
timezone | [W] | Set the timezone to use for this database, overridding `Sequel.database_timezone`.

### Public Class methods

new(opts = {}, &block)

Constructs a new instance of a database connection with the specified options hash.

Accepts the following options:

:default_schema : | The default schema to use, see default_schema.
:disconnection_proc : | A proc used to disconnect the connection
:identifier_input_method : | A string method symbol to call on identifiers going into the database
:identifier_output_method : | A string method symbol to call on identifiers coming from the database
:logger : | A specific logger to use
:loggers : | An array of loggers to use
:quote_identifiers : | Whether to quote identifiers
:servers : | A hash specifying a server/shard specific options, keyed by shard symbol
:single_threaded : | Whether to use a single-threaded connection pool
:sql_log_level : | Method to use to log SQL to a logger, :info by default.

All options given are also passed to the connection pool. If a block is given, it is used as the connection_proc for the ConnectionPool.

[Source]

        # File lib/sequel/database/misc.rb, line 64
    64:     def initialize(opts = {}, &block)
    65:       @opts ||= opts
    66:       @opts = connection_pool_default_options.merge(@opts)
    67:       @loggers = Array(@opts[:logger]) + Array(@opts[:loggers])
    68:       self.log_warn_duration = @opts[:log_warn_duration]
    69:       @opts[:disconnection_proc] ||= proc{|conn| disconnect_connection(conn)}
    70:       block ||= proc{|server| connect(server)}
    71:       @opts[:servers] = {} if @opts[:servers].is_a?(String)
    72:       @opts[:adapter_class] = self.class
    73:
    74:       @opts[:single_threaded] = @single_threaded = typecast_value_boolean(@opts.fetch(:single_threaded, @@single_threaded))
    75:       @schemas = {}
    76:       @default_schema = @opts.fetch(:default_schema, default_schema_default)
    77:       @prepared_statements = {}
    78:       @transactions = {}
    79:       @identifier_input_method = nil
    80:       @identifier_output_method = nil
    81:       @quote_identifiers = nil
    82:       @timezone = nil
    83:       @dataset_class = dataset_class_default
    84:       @cache_schema = typecast_value_boolean(@opts.fetch(:cache_schema, true))
    85:       @dataset_modules = []
    86:       self.sql_log_level = @opts[:sql_log_level] ? @opts[:sql_log_level].to_sym : :info
    87:       @pool = ConnectionPool.get_pool(@opts, &block)
    88:
    89:       Sequel.synchronize{::Sequel::DATABASES.push(self)}
    90:     end

register_extension(ext, mod=nil, &block)

Register an extension callback for Database objects. ext should be the extension name symbol, and mod should either be a Module that the database 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.

[Source]

        # File lib/sequel/database/misc.rb, line 18
    18:     def self.register_extension(ext, mod=nil, &block)
    19:       if mod
    20:         raise(Error, "cannot provide both mod and block to Database.register_extension") if block
    21:         if mod.is_a?(Module)
    22:           block = proc{|db| db.extend(mod)}
    23:         else
    24:           block = mod
    25:         end
    26:       end
    27:       Sequel.synchronize{EXTENSIONS[ext] = block}
    28:     end

### Public Instance methods

after_commit(opts={}) {|| ...}

If a transaction is not currently in process, yield to the block immediately. Otherwise, add the block to the list of blocks to call after the currently in progress transaction commits (and only if it commits). Options:

:server : | The server/shard to use.

[Source]

         # File lib/sequel/database/misc.rb, line 97
     97:     def after_commit(opts={}, &block)
     98:       raise Error, "must provide block to after_commit" unless block
     99:       synchronize(opts[:server]) do |conn|
    100:         if h = _trans(conn)
    101:           raise Error, "cannot call after_commit in a prepared transaction" if h[:prepare]
    102:           (h[:after_commit] ||= []) << block
    103:         else
    104:           yield
    105:         end
    106:       end
    107:     end

after_rollback(opts={}, &block)

If a transaction is not currently in progress, ignore the block. Otherwise, add the block to the list of the blocks to call after the currently in progress transaction rolls back (and only if it rolls back). Options:

:server : | The server/shard to use.

[Source]

         # File lib/sequel/database/misc.rb, line 114
    114:     def after_rollback(opts={}, &block)
    115:       raise Error, "must provide block to after_rollback" unless block
    116:       synchronize(opts[:server]) do |conn|
    117:         if h = _trans(conn)
    118:           raise Error, "cannot call after_rollback in a prepared transaction" if h[:prepare]
    119:           (h[:after_rollback] ||= []) << block
    120:         end
    121:       end
    122:     end

cast_type_literal(type)

Cast the given type to a literal type

      DB.cast_type_literal(Float) # double precision
      DB.cast_type_literal(:foo) # foo

[Source]

         # File lib/sequel/database/misc.rb, line 128
    128:     def cast_type_literal(type)
    129:       type_literal(:type=>type)
    130:     end

extension(*exts)

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

[Source]

         # File lib/sequel/database/misc.rb, line 137
    137:     def extension(*exts)
    138:       Sequel.extension(*exts)
    139:       exts.each do |ext|
    140:         if pr = Sequel.synchronize{EXTENSIONS[ext]}
    141:           pr.call(self)
    142:         else
    143:           raise(Error, "Extension #{ext} does not have specific support handling individual databases")
    144:         end
    145:       end
    146:       self
    147:     end

from_application_timestamp(v)

Convert the given timestamp from the application‘s timezone, to the databases‘s timezone or the default database timezone if the database does not have a timezone.

[Source]

         # File lib/sequel/database/misc.rb, line 152
    152:     def from_application_timestamp(v)
    153:       Sequel.convert_output_timestamp(v, timezone)
    154:     end

global_index_namespace?()

Whether the database uses a global namespace for the index. If false, the indexes are going to be namespaced per table.

[Source]

         # File lib/sequel/database/misc.rb, line 158
    158:     def global_index_namespace?
    159:       true
    160:     end

in_transaction?(opts={})

Return true if already in a transaction given the options, false otherwise. Respects the :server option for selecting a shard.

[Source]

         # File lib/sequel/database/misc.rb, line 165
    165:     def in_transaction?(opts={})
    166:       synchronize(opts[:server]){|conn| !!_trans(conn)}
    167:     end

inspect()

Returns a string representation of the database object including the class name and connection URI and options used when connecting (if any).

[Source]

         # File lib/sequel/database/misc.rb, line 171
    171:     def inspect
    172:       a = []
    173:       a << uri.inspect if uri
    174:       if (oo = opts[:orig_opts]) && !oo.empty?
    175:         a << oo.inspect
    176:       end
    177:       "#<#{self.class}: #{a.join(' ')}>"
    178:     end

literal(v)

Proxy the literal call to the dataset.

      DB.literal(1) # 1
      DB.literal(:a) # a
      DB.literal('a') # 'a'

[Source]

         # File lib/sequel/database/misc.rb, line 185
    185:     def literal(v)
    186:       schema_utility_dataset.literal(v)
    187:     end

prepared_statement(name)

Synchronize access to the prepared statements cache.

[Source]

         # File lib/sequel/database/misc.rb, line 190
    190:     def prepared_statement(name)
    191:       Sequel.synchronize{prepared_statements[name]}
    192:     end

serial_primary_key_options()

Default serial primary key options, used by the table creation code.

[Source]

         # File lib/sequel/database/misc.rb, line 196
    196:     def serial_primary_key_options
    197:       {:primary_key => true, :type => Integer, :auto_increment => true}
    198:     end

set_prepared_statement(name, ps)

Cache the prepared statement object at the given name.

[Source]

         # File lib/sequel/database/misc.rb, line 201
    201:     def set_prepared_statement(name, ps)
    202:       Sequel.synchronize{prepared_statements[name] = ps}
    203:     end

supports_create_table_if_not_exists?()

Whether the database supports CREATE TABLE IF NOT EXISTS syntax, false by default.

[Source]

         # File lib/sequel/database/misc.rb, line 207
    207:     def supports_create_table_if_not_exists?
    208:       false
    209:     end

supports_drop_table_if_exists?()

Whether the database supports DROP TABLE IF EXISTS syntax, default is the same as supports_create_table_if_not_exists?.

[Source]

         # File lib/sequel/database/misc.rb, line 213
    213:     def supports_drop_table_if_exists?
    214:       supports_create_table_if_not_exists?
    215:     end

supports_prepared_transactions?()

Whether the database and adapter support prepared transactions (two-phase commit), false by default.

[Source]

         # File lib/sequel/database/misc.rb, line 219
    219:     def supports_prepared_transactions?
    220:       false
    221:     end

supports_savepoints?()

Whether the database and adapter support savepoints, false by default.

[Source]

         # File lib/sequel/database/misc.rb, line 224
    224:     def supports_savepoints?
    225:       false
    226:     end

supports_savepoints_in_prepared_transactions?()

Whether the database and adapter support savepoints inside prepared transactions (two-phase commit), default is false.

[Source]

         # File lib/sequel/database/misc.rb, line 230
    230:     def supports_savepoints_in_prepared_transactions?
    231:       supports_prepared_transactions? && supports_savepoints?
    232:     end

supports_transaction_isolation_levels?()

Whether the database and adapter support transaction isolation levels, false by default.

[Source]

         # File lib/sequel/database/misc.rb, line 235
    235:     def supports_transaction_isolation_levels?
    236:       false
    237:     end

supports_transactional_ddl?()

Whether DDL statements work correctly in transactions, false by default.

[Source]

         # File lib/sequel/database/misc.rb, line 240
    240:     def supports_transactional_ddl?
    241:       false
    242:     end

timezone()

The timezone to use for this database, defaulting to `Sequel.database_timezone`.

[Source]

         # File lib/sequel/database/misc.rb, line 245
    245:     def timezone
    246:       @timezone || Sequel.database_timezone
    247:     end

to_application_timestamp(v)

Convert the given timestamp to the application‘s timezone, from the databases‘s timezone or the default database timezone if the database does not have a timezone.

[Source]

         # File lib/sequel/database/misc.rb, line 252
    252:     def to_application_timestamp(v)
    253:       Sequel.convert_timestamp(v, timezone)
    254:     end

typecast_value(column_type, value)

Typecast the value to the given column_type. Calls typecast_value_#{column_type} if the method exists, otherwise returns the value. This method should raise Sequel::InvalidValue if assigned value is invalid.

[Source]

         # File lib/sequel/database/misc.rb, line 261
    261:     def typecast_value(column_type, value)
    262:       return nil if value.nil?
    263:       meth = "typecast_value_#{column_type}"
    264:       begin
    265:         respond_to?(meth, true) ? send(meth, value) : value
    266:       rescue ArgumentError, TypeError => e
    267:         raise Sequel.convert_exception_class(e, InvalidValue)
    268:       end
    269:     end

uri()

Returns the URI use to connect to the database. If a URI was not used when connecting, returns nil.

[Source]

         # File lib/sequel/database/misc.rb, line 273
    273:     def uri
    274:       opts[:uri]
    275:     end

url()

Explicit alias of uri for easier subclassing.

[Source]

         # File lib/sequel/database/misc.rb, line 278
    278:     def url
    279:       uri
    280:     end

## 5 - Methods that set defaults for created datasets

This methods change the default behavior of this database‘s datasets.

### Constants

DatasetClass | = | Sequel::Dataset |  | The default class to use for datasets

### Attributes

dataset_class | [R] | The class to use for creating datasets. Should respond to new with the Database argument as the first argument, and an optional options hash.
default_schema | [RW] | The default schema to use, generally should be nil. This sets the default schema used for some schema modification and introspection queries, but does not effect most dataset code.

### Public Class methods

identifier_input_method()

The method to call on identifiers going into the database

[Source]

        # File lib/sequel/database/dataset_defaults.rb, line 21
    21:     def self.identifier_input_method
    22:       @@identifier_input_method
    23:     end

identifier_input_method=(v)

Set the method to call on identifiers going into the database See Sequel.identifier_input_method=.

[Source]

        # File lib/sequel/database/dataset_defaults.rb, line 27
    27:     def self.identifier_input_method=(v)
    28:       @@identifier_input_method = v || ""
    29:     end

identifier_output_method()

The method to call on identifiers coming from the database

[Source]

        # File lib/sequel/database/dataset_defaults.rb, line 32
    32:     def self.identifier_output_method
    33:       @@identifier_output_method
    34:     end

identifier_output_method=(v)

Set the method to call on identifiers coming from the database See Sequel.identifier_output_method=.

[Source]

        # File lib/sequel/database/dataset_defaults.rb, line 38
    38:     def self.identifier_output_method=(v)
    39:       @@identifier_output_method = v || ""
    40:     end

quote_identifiers=(value)

Sets the default quote_identifiers mode for new databases. See Sequel.quote_identifiers=.

[Source]

        # File lib/sequel/database/dataset_defaults.rb, line 44
    44:     def self.quote_identifiers=(value)
    45:       @@quote_identifiers = value
    46:     end

### Public Instance methods

dataset_class=(c)

If the database has any dataset modules associated with it, use a subclass of the given class that includes the modules as the dataset class.

[Source]

        # File lib/sequel/database/dataset_defaults.rb, line 61
    61:     def dataset_class=(c)
    62:       unless @dataset_modules.empty?
    63:         c = Class.new(c)
    64:         @dataset_modules.each{|m| c.send(:include, m)}
    65:       end
    66:       @dataset_class = c
    67:     end

extend_datasets(mod=nil, &block)

Equivalent to extending all datasets produced by the database with a module. What it actually does is use a subclass of the current dataset_class as the new dataset_class, and include the module in the subclass. Instead of a module, you can provide a block that is used to create an anonymous module.

This allows you to override any of the dataset methods even if they are defined directly on the dataset class that this Database object uses.

Examples:

      # Introspec columns for all of DB's datasets
      DB.extend_datasets(Sequel::ColumnsIntrospection)

      # Trace all SELECT queries by printing the SQL and the full backtrace
      DB.extend_datasets do
        def fetch_rows(sql)
          puts sql
          puts caller
          super
        end
      end

[Source]

         # File lib/sequel/database/dataset_defaults.rb, line 91
     91:     def extend_datasets(mod=nil, &block)
     92:       raise(Error, "must provide either mod or block, not both") if mod && block
     93:       reset_schema_utility_dataset
     94:       mod = Module.new(&block) if block
     95:       if @dataset_modules.empty?
     96:        @dataset_modules = [mod]
     97:        @dataset_class = Class.new(@dataset_class)
     98:       else
     99:        @dataset_modules << mod
    100:       end
    101:       @dataset_class.send(:include, mod)
    102:     end

identifier_input_method()

The method to call on identifiers going into the database

[Source]

         # File lib/sequel/database/dataset_defaults.rb, line 105
    105:     def identifier_input_method
    106:       case @identifier_input_method
    107:       when nil
    108:         @identifier_input_method = @opts.fetch(:identifier_input_method, (@@identifier_input_method.nil? ? identifier_input_method_default : @@identifier_input_method))
    109:         @identifier_input_method == "" ? nil : @identifier_input_method
    110:       when ""
    111:         nil
    112:       else
    113:         @identifier_input_method
    114:       end
    115:     end

identifier_input_method=(v)

Set the method to call on identifiers going into the database:

      DB[:items] # SELECT * FROM items
      DB.identifier_input_method = :upcase
      DB[:items] # SELECT * FROM ITEMS

[Source]

         # File lib/sequel/database/dataset_defaults.rb, line 122
    122:     def identifier_input_method=(v)
    123:       reset_schema_utility_dataset
    124:       @identifier_input_method = v || ""
    125:     end

identifier_output_method()

The method to call on identifiers coming from the database

[Source]

         # File lib/sequel/database/dataset_defaults.rb, line 128
    128:     def identifier_output_method
    129:       case @identifier_output_method
    130:       when nil
    131:         @identifier_output_method = @opts.fetch(:identifier_output_method, (@@identifier_output_method.nil? ? identifier_output_method_default : @@identifier_output_method))
    132:         @identifier_output_method == "" ? nil : @identifier_output_method
    133:       when ""
    134:         nil
    135:       else
    136:         @identifier_output_method
    137:       end
    138:     end

identifier_output_method=(v)

Set the method to call on identifiers coming from the database:

      DB[:items].first # {:id=>1, :name=>'foo'}
      DB.identifier_output_method = :upcase
      DB[:items].first # {:ID=>1, :NAME=>'foo'}

[Source]

         # File lib/sequel/database/dataset_defaults.rb, line 145
    145:     def identifier_output_method=(v)
    146:       reset_schema_utility_dataset
    147:       @identifier_output_method = v || ""
    148:     end

quote_identifiers=(v)

Set whether to quote identifiers (columns and tables) for this database:

      DB[:items] # SELECT * FROM items
      DB.quote_identifiers = true
      DB[:items] # SELECT * FROM "items"

[Source]

         # File lib/sequel/database/dataset_defaults.rb, line 155
    155:     def quote_identifiers=(v)
    156:       reset_schema_utility_dataset
    157:       @quote_identifiers = v
    158:     end

quote_identifiers?()

Returns true if the database quotes identifiers.

[Source]

         # File lib/sequel/database/dataset_defaults.rb, line 161
    161:     def quote_identifiers?
    162:       return @quote_identifiers unless @quote_identifiers.nil?
    163:       @quote_identifiers = @opts.fetch(:quote_identifiers, (@@quote_identifiers.nil? ? quote_identifiers_default : @@quote_identifiers))
    164:     end

## 6 - Methods relating to logging

This methods affect relating to the logging of executed SQL.

### Attributes

log_warn_duration | [RW] | Numeric specifying the duration beyond which queries are logged at warn level instead of info level.
loggers | [RW] | Array of SQL loggers to use for this database.
sql_log_level | [RW] | Log level at which to log SQL queries. This is actually the method sent to the logger, so it should be the method name symbol. The default is :info, it can be set to :debug to log at DEBUG level.

### Public Instance methods

log_exception(exception, message)

Log a message at error level, with information about the exception.

[Source]

        # File lib/sequel/database/logging.rb, line 21
    21:     def log_exception(exception, message)
    22:       log_each(:error, "#{exception.class}: #{exception.message.strip}: #{message}")
    23:     end

log_info(message, args=nil)

Log a message at level info to all loggers.

[Source]

        # File lib/sequel/database/logging.rb, line 26
    26:     def log_info(message, args=nil)
    27:       log_each(:info, args ? "#{message}; #{args.inspect}" : message)
    28:     end

log_yield(sql, args=nil) {|if @loggers.empty?| ...}

Yield to the block, logging any errors at error level to all loggers, and all other queries with the duration at warn or info level.

[Source]

        # File lib/sequel/database/logging.rb, line 32
    32:     def log_yield(sql, args=nil)
    33:       return yield if @loggers.empty?
    34:       sql = "#{sql}; #{args.inspect}" if args
    35:       start = Time.now
    36:       begin
    37:         yield
    38:       rescue => e
    39:         log_exception(e, sql)
    40:         raise
    41:       ensure
    42:         log_duration(Time.now - start, sql) unless e
    43:       end
    44:     end

logger=(logger)

Remove any existing loggers and just use the given logger:

      DB.logger = Logger.new($stdout)

[Source]

        # File lib/sequel/database/logging.rb, line 49
    49:     def logger=(logger)
    50:       @loggers = Array(logger)
    51:     end

## 3 - Methods that create datasets

These methods all return instances of this database‘s dataset class.

### Public Instance methods

[](*args)

Returns a dataset for the database. If the first argument is a string, the method acts as an alias for Database#fetch, returning a dataset for arbitrary SQL, with or without placeholders:

      DB['SELECT * FROM items'].all
      DB['SELECT * FROM items WHERE name = ?', my_name].all

Otherwise, acts as an alias for Database#from, setting the primary table for the dataset:

      DB[:items].sql #=> "SELECT * FROM items"

[Source]

        # File lib/sequel/database/dataset.rb, line 19
    19:     def [](*args)
    20:       (String === args.first) ? fetch(*args) : from(*args)
    21:     end

dataset(opts=nil)

Returns a blank dataset for this database.

      DB.dataset # SELECT *
      DB.dataset.from(:items) # SELECT * FROM items

[Source]

        # File lib/sequel/database/dataset.rb, line 27
    27:     def dataset(opts=nil)
    28:       @dataset_class.new(self, opts)
    29:     end

fetch(sql, *args, &block)

Fetches records for an arbitrary SQL statement. If a block is given, it is used to iterate over the records:

      DB.fetch('SELECT * FROM items'){|r| p r}

The `fetch` method returns a dataset instance:

      DB.fetch('SELECT * FROM items').all

`fetch` can also perform parameterized queries for protection against SQL injection:

      DB.fetch('SELECT * FROM items WHERE name = ?', my_name).all

[Source]

        # File lib/sequel/database/dataset.rb, line 44
    44:     def fetch(sql, *args, &block)
    45:       ds = dataset.with_sql(sql, *args)
    46:       ds.each(&block) if block
    47:       ds
    48:     end

from(*args, &block)

Returns a new dataset with the `from` method invoked. If a block is given, it is used as a filter on the dataset.

      DB.from(:items) # SELECT * FROM items
      DB.from(:items){id > 2} # SELECT * FROM items WHERE (id > 2)

[Source]

        # File lib/sequel/database/dataset.rb, line 55
    55:     def from(*args, &block)
    56:       ds = dataset.from(*args)
    57:       block ? ds.filter(&block) : ds
    58:     end

select(*args, &block)

Returns a new dataset with the select method invoked.

      DB.select(1) # SELECT 1
      DB.select{server_version{}} # SELECT server_version()
      DB.select(:id).from(:items) # SELECT id FROM items

[Source]

        # File lib/sequel/database/dataset.rb, line 65
    65:     def select(*args, &block)
    66:       dataset.select(*args, &block)
    67:     end

## 2 - Methods that modify the database schema

These methods execute code on the database that modifies the database‘s schema.

### Constants

AUTOINCREMENT | = | 'AUTOINCREMENT'.freeze
COMMA_SEPARATOR | = | ', '.freeze
NOT_NULL | = | ' NOT NULL'.freeze
NULL | = | ' NULL'.freeze
PRIMARY_KEY | = | ' PRIMARY KEY'.freeze
TEMPORARY | = | 'TEMPORARY '.freeze
UNDERSCORE | = | '_'.freeze
UNIQUE | = | ' UNIQUE'.freeze
UNSIGNED | = | ' UNSIGNED'.freeze
COLUMN_DEFINITION_ORDER | = | [:collate, :default, :null, :unique, :primary_key, :auto_increment, :references] |  | The order of column modifiers to use when defining a column.
DEFAULT_JOIN_TABLE_COLUMN_OPTIONS | = | {:null=>false} |  | The default options for join table columns.

### Public Instance methods

add_column(table, *args)

Adds a column to the specified table. This method expects a column name, a datatype and optionally a hash with additional constraints and options:

      DB.add_column :items, :name, :text, :unique => true, :null => false
      DB.add_column :items, :category, :text, :default => 'ruby'

See `alter_table`.

[Source]

        # File lib/sequel/database/schema_methods.rb, line 31
    31:     def add_column(table, *args)
    32:       alter_table(table) {add_column(*args)}
    33:     end

add_index(table, columns, options={})

Adds an index to a table for the given columns:

      DB.add_index :posts, :title
      DB.add_index :posts, [:author, :title], :unique => true

Options:

:ignore_errors : | Ignore any DatabaseErrors that are raised

See `alter_table`.

[Source]

        # File lib/sequel/database/schema_methods.rb, line 44
    44:     def add_index(table, columns, options={})
    45:       e = options[:ignore_errors]
    46:       begin
    47:         alter_table(table){add_index(columns, options)}
    48:       rescue DatabaseError
    49:         raise unless e
    50:       end
    51:     end

alter_table(name, generator=nil, &block)

Alters the given table with the specified block. Example:

      DB.alter_table :items do
        add_column :category, :text, :default => 'ruby'
        drop_column :category
        rename_column :cntr, :counter
        set_column_type :value, :float
        set_column_default :value, :float
        add_index [:group, :category]
        drop_index [:group, :category]
      end

Note that `add_column` accepts all the options available for column definitions using `create_table`, and `add_index` accepts all the options available for index definition.

See `Schema::AlterTableGenerator` and the "Migrations and Schema Modification" guide.

[Source]

        # File lib/sequel/database/schema_methods.rb, line 70
    70:     def alter_table(name, generator=nil, &block)
    71:       generator ||= alter_table_generator(&block)
    72:       remove_cached_schema(name)
    73:       apply_alter_table(name, generator.operations)
    74:       nil
    75:     end

alter_table_generator(&block)

Return a new Schema::AlterTableGenerator instance with the receiver as the database and the given block.

[Source]

        # File lib/sequel/database/schema_methods.rb, line 79
    79:     def alter_table_generator(&block)
    80:       alter_table_generator_class.new(self, &block)
    81:     end

create_join_table(hash, options={})

Create a join table using a hash of foreign keys to referenced table names. Example:

      create_join_table(:cat_id=>:cats, :dog_id=>:dogs)
      # CREATE TABLE cats_dogs (
      #  cat_id integer NOT NULL REFERENCES cats,
      #  dog_id integer NOT NULL REFERENCES dogs,
      #  PRIMARY KEY (cat_id, dog_id)
      # )
      # CREATE INDEX cats_dogs_dog_id_cat_id_index ON cats_dogs(dog_id, cat_id)

The primary key and index are used so that almost all operations on the table can benefit from one of the two indexes, and the primary key ensures that entries in the table are unique, which is the typical desire for a join table.

You can provide column options by making the values in the hash be option hashes, so long as the option hashes have a :table entry giving the table referenced:

      create_join_table(:cat_id=>{:table=>:cats, :type=>Bignum}, :dog_id=>:dogs)

You can provide a second argument which is a table options hash:

      create_join_table({:cat_id=>:cats, :dog_id=>:dogs}, :temp=>true)

Some table options are handled specially:

:index_options : | The options to pass to the index
:name : | The name of the table to create
:no_index : | Set to true not to create the second index.
:no_primary_key : | Set to true to not create the primary key.

[Source]

         # File lib/sequel/database/schema_methods.rb, line 115
    115:     def create_join_table(hash, options={})
    116:       keys = hash.keys.sort_by{|k| k.to_s}
    117:       create_table(join_table_name(hash, options), options) do
    118:         keys.each do |key|
    119:           v = hash[key]
    120:           unless v.is_a?(Hash)
    121:             v = {:table=>v}
    122:           end
    123:           v = DEFAULT_JOIN_TABLE_COLUMN_OPTIONS.merge(v)
    124:           foreign_key(key, v)
    125:         end
    126:         primary_key(keys) unless options[:no_primary_key]
    127:         index(keys.reverse, options[:index_options] || {}) unless options[:no_index]
    128:       end
    129:     end

create_or_replace_view(name, source)

Creates a view, replacing it if it already exists:

      DB.create_or_replace_view(:cheap_items, "SELECT * FROM items WHERE price < 100")
      DB.create_or_replace_view(:ruby_items, DB[:items].filter(:category => 'ruby'))

[Source]

         # File lib/sequel/database/schema_methods.rb, line 201
    201:     def create_or_replace_view(name, source)
    202:       source = source.sql if source.is_a?(Dataset)
    203:       execute_ddl("CREATE OR REPLACE VIEW #{quote_schema_table(name)} AS #{source}")
    204:       remove_cached_schema(name)
    205:       nil
    206:     end

create_table(name, options={}, &block)

Creates a table with the columns given in the provided block:

      DB.create_table :posts do
        primary_key :id
        column :title, :text
        String :content
        index :title
      end

General options:

:as : | Create the table using the value, which should be either a dataset or a literal SQL string. If this option is used, a block should not be given to the method.
:ignore_index_errors : | Ignore any errors when creating indexes.
:temp : | Create the table as a temporary table.

MySQL specific options:

:charset : | The character set to use for the table.
:collate : | The collation to use for the table.
:engine : | The table engine to use for the table.

See `Schema::Generator` and the "Schema Modification" guide.

[Source]

         # File lib/sequel/database/schema_methods.rb, line 153
    153:     def create_table(name, options={}, &block)
    154:       remove_cached_schema(name)
    155:       options = {:generator=>options} if options.is_a?(Schema::CreateTableGenerator)
    156:       if sql = options[:as]
    157:         raise(Error, "can't provide both :as option and block to create_table") if block
    158:         create_table_as(name, sql, options)
    159:       else
    160:         generator = options[:generator] || create_table_generator(&block)
    161:         create_table_from_generator(name, generator, options)
    162:         create_table_indexes_from_generator(name, generator, options)
    163:         nil
    164:       end
    165:     end

create_table!(name, options={}, &block)

Forcibly create a table, attempting to drop it if it already exists, then creating it.

      DB.create_table!(:a){Integer :a}
      # SELECT NULL FROM a LIMIT 1 -- check existence
      # DROP TABLE a -- drop table if already exists
      # CREATE TABLE a (a integer)

[Source]

         # File lib/sequel/database/schema_methods.rb, line 173
    173:     def create_table!(name, options={}, &block)
    174:       drop_table?(name)
    175:       create_table(name, options, &block)
    176:     end

create_table?(name, options={}, &block)

Creates the table unless the table already exists.

      DB.create_table?(:a){Integer :a}
      # SELECT NULL FROM a LIMIT 1 -- check existence
      # CREATE TABLE a (a integer) -- if it doesn't already exist

[Source]

         # File lib/sequel/database/schema_methods.rb, line 183
    183:     def create_table?(name, options={}, &block)
    184:       if supports_create_table_if_not_exists?
    185:         create_table(name, options.merge(:if_not_exists=>true), &block)
    186:       elsif !table_exists?(name)
    187:         create_table(name, options, &block)
    188:       end
    189:     end

create_table_generator(&block)

Return a new Schema::CreateTableGenerator instance with the receiver as the database and the given block.

[Source]

         # File lib/sequel/database/schema_methods.rb, line 193
    193:     def create_table_generator(&block)
    194:       create_table_generator_class.new(self, &block)
    195:     end

create_view(name, source)

Creates a view based on a dataset or an SQL string:

      DB.create_view(:cheap_items, "SELECT * FROM items WHERE price < 100")
      DB.create_view(:ruby_items, DB[:items].filter(:category => 'ruby'))

[Source]

         # File lib/sequel/database/schema_methods.rb, line 212
    212:     def create_view(name, source)
    213:       source = source.sql if source.is_a?(Dataset)
    214:       execute_ddl("CREATE VIEW #{quote_schema_table(name)} AS #{source}")
    215:     end

drop_column(table, *args)

Removes a column from the specified table:

      DB.drop_column :items, :category

See `alter_table`.

[Source]

         # File lib/sequel/database/schema_methods.rb, line 222
    222:     def drop_column(table, *args)
    223:       alter_table(table) {drop_column(*args)}
    224:     end

drop_index(table, columns, options={})

Removes an index for the given table and column/s:

      DB.drop_index :posts, :title
      DB.drop_index :posts, [:author, :title]

See `alter_table`.

[Source]

         # File lib/sequel/database/schema_methods.rb, line 232
    232:     def drop_index(table, columns, options={})
    233:       alter_table(table){drop_index(columns, options)}
    234:     end

drop_join_table(hash, options={})

Drop the join table that would have been created with the same arguments to create_join_table:

      drop_join_table(:cat_id=>:cats, :dog_id=>:dogs)
      # DROP TABLE cats_dogs

[Source]

         # File lib/sequel/database/schema_methods.rb, line 241
    241:     def drop_join_table(hash, options={})
    242:       drop_table(join_table_name(hash, options), options)
    243:     end

drop_table(*names)

Drops one or more tables corresponding to the given names:

      DB.drop_table(:posts) # DROP TABLE posts
      DB.drop_table(:posts, :comments)
      DB.drop_table(:posts, :comments, :cascade=>true)

[Source]

         # File lib/sequel/database/schema_methods.rb, line 250
    250:     def drop_table(*names)
    251:       options = names.last.is_a?(Hash) ? names.pop : {}
    252:       names.each do |n|
    253:         execute_ddl(drop_table_sql(n, options))
    254:         remove_cached_schema(n)
    255:       end
    256:       nil
    257:     end

drop_table?(*names)

Drops the table if it already exists. If it doesn‘t exist, does nothing.

      DB.drop_table?(:a)
      # SELECT NULL FROM a LIMIT 1 -- check existence
      # DROP TABLE a -- if it already exists

[Source]

         # File lib/sequel/database/schema_methods.rb, line 265
    265:     def drop_table?(*names)
    266:       options = names.last.is_a?(Hash) ? names.pop : {}
    267:       if supports_drop_table_if_exists?
    268:         options = options.merge(:if_exists=>true)
    269:         names.each do |name|
    270:           drop_table(name, options)
    271:         end
    272:       else
    273:         names.each do |name|
    274:           drop_table(name, options) if table_exists?(name)
    275:         end
    276:       end
    277:     end

drop_view(*names)

Drops one or more views corresponding to the given names:

      DB.drop_view(:cheap_items)
      DB.drop_view(:cheap_items, :pricey_items)
      DB.drop_view(:cheap_items, :pricey_items, :cascade=>true)

[Source]

         # File lib/sequel/database/schema_methods.rb, line 284
    284:     def drop_view(*names)
    285:       options = names.last.is_a?(Hash) ? names.pop : {}
    286:       names.each do |n|
    287:         execute_ddl(drop_view_sql(n, options))
    288:         remove_cached_schema(n)
    289:       end
    290:       nil
    291:     end

rename_column(table, *args)

Renames a column in the specified table. This method expects the current column name and the new column name:

      DB.rename_column :items, :cntr, :counter

See `alter_table`.

[Source]

         # File lib/sequel/database/schema_methods.rb, line 310
    310:     def rename_column(table, *args)
    311:       alter_table(table) {rename_column(*args)}
    312:     end

rename_table(name, new_name)

Renames a table:

      DB.tables #=> [:items]
      DB.rename_table :items, :old_items
      DB.tables #=> [:old_items]

[Source]

         # File lib/sequel/database/schema_methods.rb, line 298
    298:     def rename_table(name, new_name)
    299:       execute_ddl(rename_table_sql(name, new_name))
    300:       remove_cached_schema(name)
    301:       nil
    302:     end

set_column_default(table, *args)

Sets the default value for the given column in the given table:

      DB.set_column_default :items, :category, 'perl!'

See `alter_table`.

[Source]

         # File lib/sequel/database/schema_methods.rb, line 319
    319:     def set_column_default(table, *args)
    320:       alter_table(table) {set_column_default(*args)}
    321:     end

set_column_type(table, *args)

Set the data type for the given column in the given table:

      DB.set_column_type :items, :price, :float

See `alter_table`.

[Source]

         # File lib/sequel/database/schema_methods.rb, line 328
    328:     def set_column_type(table, *args)
    329:       alter_table(table) {set_column_type(*args)}
    330:     end

## 1 - Methods that execute queries and/or return results

This methods generally execute SQL code on the database server.

### Constants

SQL_BEGIN | = | 'BEGIN'.freeze
SQL_COMMIT | = | 'COMMIT'.freeze
SQL_RELEASE_SAVEPOINT | = | 'RELEASE SAVEPOINT autopoint_%d'.freeze
SQL_ROLLBACK | = | 'ROLLBACK'.freeze
SQL_ROLLBACK_TO_SAVEPOINT | = | 'ROLLBACK TO SAVEPOINT autopoint_%d'.freeze
SQL_SAVEPOINT | = | 'SAVEPOINT autopoint_%d'.freeze
TRANSACTION_BEGIN | = | 'Transaction.begin'.freeze
TRANSACTION_COMMIT | = | 'Transaction.commit'.freeze
TRANSACTION_ROLLBACK | = | 'Transaction.rollback'.freeze
TRANSACTION_ISOLATION_LEVELS | = | {:uncommitted=>'READ UNCOMMITTED'.freeze, :committed=>'READ COMMITTED'.freeze, :repeatable=>'REPEATABLE READ'.freeze, :serializable=>'SERIALIZABLE'.freeze}
POSTGRES_DEFAULT_RE | = | /\A(?:B?('.*')::[^']+|\((-?\d+(?:\.\d+)?)\))\z/
MSSQL_DEFAULT_RE | = | /\A(?:\(N?('.*')\)|\(\((-?\d+(?:\.\d+)?)\)\))\z/
MYSQL_TIMESTAMP_RE | = | /\ACURRENT_(?:DATE|TIMESTAMP)?\z/
STRING_DEFAULT_RE | = | /\A'(.*)'\z/

### Attributes

cache_schema | [RW] | Whether the schema should be cached for this database. True by default for performance, can be set to false to always issue a database query to get the schema.
prepared_statements | [R] | The prepared statement object hash for this database, keyed by name symbol
transaction_isolation_level | [RW] | The default transaction isolation level for this database, used for all future transactions. For MSSQL, this should be set to something if you ever plan to use the :isolation option to Database#transaction, as on MSSQL if affects all future transactions on the same connection.

### Public Instance methods

<<(sql)

Runs the supplied SQL statement string on the database server. Returns self so it can be safely chained:

      DB << "UPDATE albums SET artist_id = NULL" << "DROP TABLE artists"

[Source]

        # File lib/sequel/database/query.rb, line 48
    48:     def <<(sql)
    49:       run(sql)
    50:       self
    51:     end

call(ps_name, hash={}, &block)

Call the prepared statement with the given name with the given hash of arguments.

      DB[:items].filter(:id=>1).prepare(:first, :sa)
      DB.call(:sa) # SELECT * FROM items WHERE id = 1

[Source]

        # File lib/sequel/database/query.rb, line 58
    58:     def call(ps_name, hash={}, &block)
    59:       prepared_statement(ps_name).call(hash, &block)
    60:     end

execute(sql, opts={})

Executes the given SQL on the database. This method should be overridden in descendants. This method should not be called directly by user code.

[Source]

        # File lib/sequel/database/query.rb, line 64
    64:     def execute(sql, opts={})
    65:       raise NotImplemented, "#execute should be overridden by adapters"
    66:     end

execute_ddl(sql, opts={}, &block)

Method that should be used when submitting any DDL (Data Definition Language) SQL, such as `create_table`. By default, calls `execute_dui`. This method should not be called directly by user code.

[Source]

        # File lib/sequel/database/query.rb, line 71
    71:     def execute_ddl(sql, opts={}, &block)
    72:       execute_dui(sql, opts, &block)
    73:     end

execute_dui(sql, opts={}, &block)

Method that should be used when issuing a DELETE, UPDATE, or INSERT statement. By default, calls execute. This method should not be called directly by user code.

[Source]

        # File lib/sequel/database/query.rb, line 78
    78:     def execute_dui(sql, opts={}, &block)
    79:       execute(sql, opts, &block)
    80:     end

execute_insert(sql, opts={}, &block)

Method that should be used when issuing a INSERT statement. By default, calls execute_dui. This method should not be called directly by user code.

[Source]

        # File lib/sequel/database/query.rb, line 85
    85:     def execute_insert(sql, opts={}, &block)
    86:       execute_dui(sql, opts, &block)
    87:     end

foreign_key_list(table, opts={})

Returns an array of hashes containing foreign key information from the table. Each hash will contain at least the following fields:

:columns : | An array of columns in the given table
:table : | The table referenced by the columns
:key : | An array of columns referenced (in the table specified by :table), but can be nil on certain adapters if the primary key is referenced.

The hash may also contain entries for:

:deferrable : | Whether the constraint is deferrable
:name : | The name of the constraint
:on_delete : | The action to take ON DELETE
:on_update : | The action to take ON UPDATE

[Source]

         # File lib/sequel/database/query.rb, line 103
    103:     def foreign_key_list(table, opts={})
    104:       raise NotImplemented, "#foreign_key_list should be overridden by adapters"
    105:     end

get(*args, &block)

Returns a single value from the database, e.g.:

      DB.get(1) # SELECT 1
      # => 1
      DB.get{server_version{}} # SELECT server_version()

[Source]

         # File lib/sequel/database/query.rb, line 112
    112:     def get(*args, &block)
    113:       dataset.get(*args, &block)
    114:     end

indexes(table, opts={})

Return a hash containing index information for the table. Hash keys are index name symbols. Values are subhashes with two keys, :columns and :unique. The value of :columns is an array of symbols of column names. The value of :unique is true or false depending on if the index is unique.

Should not include the primary key index, functional indexes, or partial indexes.

      DB.indexes(:artists)
      # => {:artists_name_ukey=>{:columns=>[:name], :unique=>true}}

[Source]

         # File lib/sequel/database/query.rb, line 125
    125:     def indexes(table, opts={})
    126:       raise NotImplemented, "#indexes should be overridden by adapters"
    127:     end

run(sql, opts={})

Runs the supplied SQL statement string on the database server. Returns nil. Options:

:server : | The server to run the SQL on.

      DB.run("SET some_server_variable = 42")

[Source]

         # File lib/sequel/database/query.rb, line 134
    134:     def run(sql, opts={})
    135:       execute_ddl(sql, opts)
    136:       nil
    137:     end

schema(table, opts={})

Returns the schema for the given table as an array with all members being arrays of length 2, the first member being the column name, and the second member being a hash of column information. The table argument can also be a dataset, as long as it only has one table. Available options are:

:reload : | Ignore any cached results, and get fresh information from the database.
:schema : | An explicit schema to use. It may also be implicitly provided via the table name.

If schema parsing is supported by the database, the column information should hash at least contain the following entries:

:allow_null : | Whether NULL is an allowed value for the column.
:db_type : | The database type for the column, as a database specific string.
:default : | The database default for the column, as a database specific string.
:primary_key : | Whether the columns is a primary key column. If this column is not present, it means that primary key information is unavailable, not that the column is not a primary key.
:ruby_default : | The database default for the column, as a ruby object. In many cases, complex database defaults cannot be parsed into ruby objects, in which case nil will be used as the value.
:type : | A symbol specifying the type, such as :integer or :string.

Example:

      DB.schema(:artists)
      # [[:id,
      #   {:type=>:integer,
      #    :primary_key=>true,
      #    :default=>"nextval('artist_id_seq'::regclass)",
      #    :ruby_default=>nil,
      #    :db_type=>"integer",
      #    :allow_null=>false}],
      #  [:name,
      #   {:type=>:string,
      #    :primary_key=>false,
      #    :default=>nil,
      #    :ruby_default=>nil,
      #    :db_type=>"text",
      #    :allow_null=>false}]]

[Source]

         # File lib/sequel/database/query.rb, line 179
    179:     def schema(table, opts={})
    180:       raise(Error, 'schema parsing is not implemented on this database') unless respond_to?(:schema_parse_table, true)
    181:
    182:       opts = opts.dup
    183:       if table.is_a?(Dataset)
    184:         o = table.opts
    185:         from = o[:from]
    186:         raise(Error, "can only parse the schema for a dataset with a single from table") unless from && from.length == 1 && !o.include?(:join) && !o.include?(:sql)
    187:         tab = table.first_source_table
    188:         sch, table_name = schema_and_table(tab)
    189:         quoted_name = table.literal(tab)
    190:         opts[:dataset] = table
    191:       else
    192:         sch, table_name = schema_and_table(table)
    193:         quoted_name = quote_schema_table(table)
    194:       end
    195:       opts[:schema] = sch if sch && !opts.include?(:schema)
    196:
    197:       Sequel.synchronize{@schemas.delete(quoted_name)} if opts[:reload]
    198:       return Sequel.synchronize{@schemas[quoted_name]} if @schemas[quoted_name]
    199:
    200:       cols = schema_parse_table(table_name, opts)
    201:       raise(Error, 'schema parsing returned no columns, table probably doesn\'t exist') if cols.nil? || cols.empty?
    202:       cols.each{|_,c| c[:ruby_default] = column_schema_to_ruby_default(c[:default], c[:type])}
    203:       Sequel.synchronize{@schemas[quoted_name] = cols} if cache_schema
    204:       cols
    205:     end

table_exists?(name)

Returns true if a table with the given name exists. This requires a query to the database.

      DB.table_exists?(:foo) # => false
      # SELECT NULL FROM foo LIMIT 1

Note that since this does a SELECT from the table, it can give false negatives if you don‘t have permission to SELECT from the table.

[Source]

         # File lib/sequel/database/query.rb, line 215
    215:     def table_exists?(name)
    216:       sch, table_name = schema_and_table(name)
    217:       name = SQL::QualifiedIdentifier.new(sch, table_name) if sch
    218:       _table_exists?(from(name))
    219:       true
    220:     rescue DatabaseError
    221:       false
    222:     end

tables(opts={})

Return all tables in the database as an array of symbols.

      DB.tables # => [:albums, :artists]

[Source]

         # File lib/sequel/database/query.rb, line 227
    227:     def tables(opts={})
    228:       raise NotImplemented, "#tables should be overridden by adapters"
    229:     end

transaction(opts={}) {|conn| ...}

Starts a database transaction. When a database transaction is used, either all statements are successful or none of the statements are successful. Note that MySQL MyISAM tabels do not support transactions.

The following general options are respected:

:isolation : | The transaction isolation level to use for this transaction, should be :uncommitted, :committed, :repeatable, or :serializable, used if given and the database/adapter supports customizable transaction isolation levels.
:prepare : | A string to use as the transaction identifier for a prepared transaction (two-phase commit), if the database/adapter supports prepared transactions.
:rollback : | Can the set to :reraise to reraise any Sequel::Rollback exceptions raised, or :always to always rollback even if no exceptions occur (useful for testing).
:server : | The server to use for the transaction.
:savepoint : | Whether to create a new savepoint for this transaction, only respected if the database/adapter supports savepoints. By default Sequel will reuse an existing transaction, so if you want to use a savepoint you must use this option.

PostgreSQL specific options:

:deferrable : | (9.1+) If present, set to DEFERRABLE if true or NOT DEFERRABLE if false.
:read_only : | If present, set to READ ONLY if true or READ WRITE if false.
:synchronous : | if non-nil, set synchronous_commit appropriately. Valid values true, :on, false, :off, :local (9.1+), and :remote_write (9.2+).

[Source]

         # File lib/sequel/database/query.rb, line 260
    260:     def transaction(opts={}, &block)
    261:       synchronize(opts[:server]) do |conn|
    262:         return yield(conn) if already_in_transaction?(conn, opts)
    263:         _transaction(conn, opts, &block)
    264:       end
    265:     end

views(opts={})

Return all views in the database as an array of symbols.

      DB.views # => [:gold_albums, :artists_with_many_albums]

[Source]

         # File lib/sequel/database/query.rb, line 270
    270:     def views(opts={})
    271:       raise NotImplemented, "#views should be overridden by adapters"
    272:     end

## 4 - Methods relating to adapters, connecting, disconnecting, and sharding

This methods involve the Database‘s connection pool.

### Constants

ADAPTERS | = | %w'ado amalgalite db2 dbi do firebird ibmdb informix jdbc mock mysql mysql2 odbc openbase oracle postgres sqlite swift tinytds'.collect{|x| x.to_sym} |  | Array of supported database adapters
DISCONNECT_ERROR_RE | = | /terminating connection due to administrator command/
MYSQL_DATABASE_DISCONNECT_ERRORS | = | /\A(Commands out of sync; you can't run this command now|Can't connect to local MySQL server through socket|MySQL server has gone away|Lost connection to MySQL server during query)/ |  | Mysql::Error messages that indicate the current connection should be disconnected
AFFECTED_ROWS_RE | = | /Rows matched:\s+(\d+)\s+Changed:\s+\d+\s+Warnings:\s+\d+/.freeze |  | Regular expression used for getting accurate number of rows matched by an update statement.

### Attributes

conversion_procs | [R] | The conversion procs to use for this database
conversion_procs | [R] | Hash of conversion procs for the current database
convert_invalid_date_time | [R] | By default, Sequel raises an exception if in invalid date or time is used. However, if this is set to nil or :nil, the adapter treats dates like 0000-00-00 and times like 838:00:00 as nil values. If set to :string, it returns the strings as is.
convert_tinyint_to_bool | [R] | Whether to convert tinyint columns to bool for the current database
convert_types | [RW] | Whether to convert some Java types to ruby types when retrieving rows. True by default, can be set to false to roughly double performance when fetching rows.
database_type | [R] | The type of database we are connecting to
driver | [R] | The Java database driver we are using
pool | [R] | The connection pool for this Database instance. All Database instances have their own connection pools.
swift_class | [RW] | The Swift adapter class being used by this database. Connections in this database‘s connection pool will be instances of this class.

### Public Class methods

adapter_class(scheme)

The Database subclass for the given adapter scheme. Raises Sequel::AdapterNotFound if the adapter could not be loaded.

[Source]

        # File lib/sequel/database/connecting.rb, line 17
    17:     def self.adapter_class(scheme)
    18:       return scheme if scheme.is_a?(Class)
    19:
    20:       scheme = scheme.to_s.gsub('-', '_').to_sym
    21:
    22:       unless klass = ADAPTER_MAP[scheme]
    23:         # attempt to load the adapter file
    24:         begin
    25:           Sequel.tsk_require "sequel/adapters/#{scheme}"
    26:         rescue LoadError => e
    27:           raise Sequel.convert_exception_class(e, AdapterNotFound)
    28:         end
    29:
    30:         # make sure we actually loaded the adapter
    31:         unless klass = ADAPTER_MAP[scheme]
    32:           raise AdapterNotFound, "Could not load #{scheme} adapter: adapter class not registered in ADAPTER_MAP"
    33:         end
    34:       end
    35:       klass
    36:     end

adapter_scheme()

Returns the scheme symbol for the Database class.

[Source]

        # File lib/sequel/database/connecting.rb, line 39
    39:     def self.adapter_scheme
    40:       @scheme
    41:     end

connect(conn_string, opts = {}) {|db| ...}

Connects to a database. See Sequel.connect.

[Source]

        # File lib/sequel/database/connecting.rb, line 44
    44:     def self.connect(conn_string, opts = {})
    45:       case conn_string
    46:       when String
    47:         if match = /\A(jdbc|do):/o.match(conn_string)
    48:           c = adapter_class(match[1].to_sym)
    49:           opts = opts.merge(:orig_opts=>opts.dup)
    50:           opts = {:uri=>conn_string}.merge(opts)
    51:         else
    52:           uri = URI.parse(conn_string)
    53:           scheme = uri.scheme
    54:           scheme = :dbi if scheme =~ /\Adbi-/
    55:           c = adapter_class(scheme)
    56:           uri_options = c.send(:uri_to_options, uri)
    57:           uri.query.split('&').collect{|s| s.split('=')}.each{|k,v| uri_options[k.to_sym] = v if k && !k.empty?} unless uri.query.to_s.strip.empty?
    58:           uri_options.to_a.each{|k,v| uri_options[k] = URI.unescape(v) if v.is_a?(String)}
    59:           opts = opts.merge(:orig_opts=>opts.dup)
    60:           opts[:uri] = conn_string
    61:           opts = uri_options.merge(opts)
    62:           opts[:adapter] = scheme
    63:         end
    64:       when Hash
    65:         opts = conn_string.merge(opts)
    66:         opts = opts.merge(:orig_opts=>opts.dup)
    67:         c = adapter_class(opts[:adapter_class] || opts[:adapter] || opts['adapter'])
    68:       else
    69:         raise Error, "Sequel::Database.connect takes either a Hash or a String, given: #{conn_string.inspect}"
    70:       end
    71:       # process opts a bit
    72:       opts = opts.inject({}) do |m, (k,v)|
    73:         k = :user if k.to_s == 'username'
    74:         m[k.to_sym] = v
    75:         m
    76:       end
    77:       begin
    78:         db = c.new(opts)
    79:         db.test_connection if opts[:test] && db.send(:typecast_value_boolean, opts[:test])
    80:         result = yield(db) if block_given?
    81:       ensure
    82:         if block_given?
    83:           db.disconnect if db
    84:           Sequel.synchronize{::Sequel::DATABASES.delete(db)}
    85:         end
    86:       end
    87:       block_given? ? result : db
    88:     end

new(opts)

Call the DATABASE_SETUP proc directly after initialization, so the object always uses sub adapter specific code. Also, raise an error immediately if the connection doesn‘t have a db_type specified, since one is required to include the correct subadapter.

[Source]

        # File lib/sequel/adapters/swift.rb, line 45
    45:       def initialize(opts)
    46:         super
    47:         if db_type = opts[:db_type] and !db_type.to_s.empty?
    48:           if prok = DATABASE_SETUP[db_type.to_s.to_sym]
    49:             prok.call(self)
    50:           else
    51:             raise(Error, "No :db_type option specified")
    52:           end
    53:         else
    54:           raise(Error, ":db_type option not valid, should be postgres, mysql, or sqlite")
    55:         end
    56:       end

new(opts)

Call the DATABASE_SETUP proc directly after initialization, so the object always uses sub adapter specific code. Also, raise an error immediately if the connection doesn‘t have a uri, since DataObjects requires one.

[Source]

        # File lib/sequel/adapters/do.rb, line 51
    51:       def initialize(opts)
    52:         super
    53:         raise(Error, "No connection string specified") unless uri
    54:         if prok = DATABASE_SETUP[subadapter.to_sym]
    55:           prok.call(self)
    56:         end
    57:       end

new(opts={})

[Source]

        # File lib/sequel/adapters/sqlite.rb, line 94
    94:       def initialize(opts={})
    95:         super
    96:         @conversion_procs = SQLITE_TYPES.dup
    97:         @conversion_procs['datetime'] = @conversion_procs['timestamp'] = method(:to_application_timestamp)
    98:         set_integer_booleans
    99:       end

new(opts={})

[Source]

        # File lib/sequel/adapters/mysql.rb, line 65
    65:       def initialize(opts={})
    66:         super
    67:         @conversion_procs = MYSQL_TYPES.dup
    68:         self.convert_tinyint_to_bool = Sequel::MySQL.convert_tinyint_to_bool
    69:         self.convert_invalid_date_time = Sequel::MySQL.convert_invalid_date_time
    70:       end

new(opts)

Call the DATABASE_SETUP proc directly after initialization, so the object always uses sub adapter specific code. Also, raise an error immediately if the connection doesn‘t have a uri, since JDBC requires one.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 158
    158:       def initialize(opts)
    159:         super
    160:         @connection_prepared_statements = {}
    161:         @connection_prepared_statements_mutex = Mutex.new
    162:         @convert_types = typecast_value_boolean(@opts.fetch(:convert_types, true))
    163:         raise(Error, "No connection string specified") unless uri
    164:
    165:         resolved_uri = jndi? ? get_uri_from_jndi : uri
    166:
    167:         if match = /\Ajdbc:([^:]+)/.match(resolved_uri) and prok = DATABASE_SETUP[match[1].to_sym]
    168:           @driver = prok.call(self)
    169:         end
    170:       end

single_threaded=(value)

Sets the default single_threaded mode for new databases. See Sequel.single_threaded=.

[Source]

        # File lib/sequel/database/connecting.rb, line 92
    92:     def self.single_threaded=(value)
    93:       @@single_threaded = value
    94:     end

### Public Instance methods

adapter_scheme()

Returns the scheme symbol for this instance‘s class, which reflects which adapter is being used. In some cases, this can be the same as the `database_type` (for native adapters), in others (i.e. adapters with subadapters), it will be different.

      Sequel.connect('jdbc:postgres://...').adapter_scheme # => :jdbc

[Source]

         # File lib/sequel/database/connecting.rb, line 124
    124:     def adapter_scheme
    125:       self.class.adapter_scheme
    126:     end

add_servers(servers)

Dynamically add new servers or modify server options at runtime. Also adds new servers to the connection pool. Intended for use with master/slave or shard configurations where it is useful to add new server hosts at runtime.

servers argument should be a hash with server name symbol keys and hash or proc values. If a servers key is already in use, it‘s value is overridden with the value provided.

      DB.add_servers(:f=>{:host=>"hash_host_f"})

[Source]

         # File lib/sequel/database/connecting.rb, line 137
    137:     def add_servers(servers)
    138:       if h = @opts[:servers]
    139:         Sequel.synchronize{h.merge!(servers)}
    140:         @pool.add_servers(servers.keys)
    141:       end
    142:     end

call_sproc(name, opts = {}) {|log_yield(sql){cps.executeQuery}| ...}

Execute the given stored procedure with the give name. If a block is given, the stored procedure should return rows.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 174
    174:       def call_sproc(name, opts = {})
    175:         args = opts[:args] || []
    176:         sql = "{call #{name}(#{args.map{'?'}.join(',')})}"
    177:         synchronize(opts[:server]) do |conn|
    178:           cps = conn.prepareCall(sql)
    179:
    180:           i = 0
    181:           args.each{|arg| set_ps_arg(cps, arg, i+=1)}
    182:
    183:           begin
    184:             if block_given?
    185:               yield log_yield(sql){cps.executeQuery}
    186:             else
    187:               case opts[:type]
    188:               when :insert
    189:                 log_yield(sql){cps.executeUpdate}
    190:                 last_insert_id(conn, opts)
    191:               else
    192:                 log_yield(sql){cps.executeUpdate}
    193:               end
    194:             end
    195:           rescue NativeException, JavaSQL::SQLException => e
    196:             raise_error(e)
    197:           ensure
    198:             cps.close
    199:           end
    200:         end
    201:       end

connect(server)

Connect to the database. Since SQLite is a file based database, the only options available are :database (to specify the database name), and :timeout, to specify how long to wait for the database to be available if it is locked, given in milliseconds (default is 5000).

[Source]

         # File lib/sequel/adapters/sqlite.rb, line 105
    105:       def connect(server)
    106:         opts = server_opts(server)
    107:         opts[:database] = ':memory:' if blank_object?(opts[:database])
    108:         db = ::SQLite3::Database.new(opts[:database])
    109:         db.busy_timeout(opts.fetch(:timeout, 5000))
    110:
    111:         connection_pragmas.each{|s| log_yield(s){db.execute_batch(s)}}
    112:
    113:         class << db
    114:           attr_reader :prepared_statements
    115:         end
    116:         db.instance_variable_set(:@prepared_statements, {})
    117:
    118:         db
    119:       end

connect(server)

Create an instance of swift_class for the given options.

[Source]

        # File lib/sequel/adapters/swift.rb, line 59
    59:       def connect(server)
    60:         opts = server_opts(server)
    61:         opts[:pass] = opts[:password]
    62:         setup_connection(swift_class.new(opts))
    63:       end

connect(server)

Setup a DataObjects::Connection to the database.

[Source]

        # File lib/sequel/adapters/do.rb, line 60
    60:       def connect(server)
    61:         setup_connection(::DataObjects::Connection.new(uri(server_opts(server))))
    62:       end

connect(server)

Connect to the database. In addition to the usual database options, the following options have effect:

- :auto_is_null - Set to true to use MySQL default behavior of having a filter for an autoincrement column equals NULL to return the last inserted row.
- :charset - Same as :encoding (:encoding takes precendence)
- :compress - Set to false to not compress results from the server
- :config_default_group - The default group to read from the in the MySQL config file.
- :config_local_infile - If provided, sets the Mysql::OPT_LOCAL_INFILE option on the connection with the given value.
- :connect_timeout - Set the timeout in seconds before a connection attempt is abandoned.
- :encoding - Set all the related character sets for this connection (connection, client, database, server, and results).
- :read_timeout - Set the timeout in seconds for reading back results to a query.
- :socket - Use a unix socket file instead of connecting via TCP/IP.
- :timeout - Set the timeout in seconds before the server will disconnect this connection (a.k.a @@wait_timeout).

[Source]

         # File lib/sequel/adapters/mysql.rb, line 93
     93:       def connect(server)
     94:         opts = server_opts(server)
     95:         conn = Mysql.init
     96:         conn.options(Mysql::READ_DEFAULT_GROUP, opts[:config_default_group] || "client")
     97:         conn.options(Mysql::OPT_LOCAL_INFILE, opts[:config_local_infile]) if opts.has_key?(:config_local_infile)
     98:         conn.ssl_set(opts[:sslkey], opts[:sslcert], opts[:sslca], opts[:sslcapath], opts[:sslcipher]) if opts[:sslca] || opts[:sslkey]
     99:         if encoding = opts[:encoding] || opts[:charset]
    100:           # Set encoding before connecting so that the mysql driver knows what
    101:           # encoding we want to use, but this can be overridden by READ_DEFAULT_GROUP.
    102:           conn.options(Mysql::SET_CHARSET_NAME, encoding)
    103:         end
    104:         if read_timeout = opts[:read_timeout] and defined? Mysql::OPT_READ_TIMEOUT
    105:           conn.options(Mysql::OPT_READ_TIMEOUT, read_timeout)
    106:         end
    107:         if connect_timeout = opts[:connect_timeout] and defined? Mysql::OPT_CONNECT_TIMEOUT
    108:           conn.options(Mysql::OPT_CONNECT_TIMEOUT, connect_timeout)
    109:         end
    110:         conn.real_connect(
    111:           opts[:host] || 'localhost',
    112:           opts[:user],
    113:           opts[:password],
    114:           opts[:database],
    115:           (opts[:port].to_i if opts[:port]),
    116:           opts[:socket],
    117:           Mysql::CLIENT_MULTI_RESULTS +
    118:           Mysql::CLIENT_MULTI_STATEMENTS +
    119:           (opts[:compress] == false ? 0 : Mysql::CLIENT_COMPRESS)
    120:         )
    121:         sqls = mysql_connection_setting_sqls
    122:
    123:         # Set encoding a slightly different way after connecting,
    124:         # in case the READ_DEFAULT_GROUP overrode the provided encoding.
    125:         # Doesn't work across implicit reconnects, but Sequel doesn't turn on
    126:         # that feature.
    127:         sqls.unshift("SET NAMES #{literal(encoding.to_s)}") if encoding
    128:
    129:         sqls.each{|sql| log_yield(sql){conn.query(sql)}}
    130:
    131:         add_prepared_statements_cache(conn)
    132:         conn
    133:       end

connect(server)

Connects to the database. This method should be overridden by descendants.

[Source]

         # File lib/sequel/database/connecting.rb, line 145
    145:     def connect(server)
    146:       raise NotImplemented, "#connect should be overridden by adapters"
    147:     end

connect(server)

Connect to the database using JavaSQL::DriverManager.getConnection.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 204
    204:       def connect(server)
    205:         opts = server_opts(server)
    206:         conn = if jndi?
    207:           get_connection_from_jndi
    208:         else
    209:           args = [uri(opts)]
    210:           args.concat([opts[:user], opts[:password]]) if opts[:user] && opts[:password]
    211:           begin
    212:             JavaSQL::DriverManager.setLoginTimeout(opts[:login_timeout]) if opts[:login_timeout]
    213:             JavaSQL::DriverManager.getConnection(*args)
    214:           rescue JavaSQL::SQLException, NativeException, StandardError => e
    215:             raise e unless driver
    216:             # If the DriverManager can't get the connection - use the connect
    217:             # method of the driver. (This happens under Tomcat for instance)
    218:             props = java.util.Properties.new
    219:             if opts && opts[:user] && opts[:password]
    220:               props.setProperty("user", opts[:user])
    221:               props.setProperty("password", opts[:password])
    222:             end
    223:             opts[:jdbc_properties].each{|k,v| props.setProperty(k.to_s, v)} if opts[:jdbc_properties]
    224:             begin
    225:               c = driver.new.connect(args[0], props)
    226:               raise(Sequel::DatabaseError, 'driver.new.connect returned nil: probably bad JDBC connection string') unless c
    227:               c
    228:             rescue JavaSQL::SQLException, NativeException, StandardError => e2
    229:               e.message << "\n#{e2.class.name}: #{e2.message}"
    230:               raise e
    231:             end
    232:           end
    233:         end
    234:         setup_connection(conn)
    235:       end

convert_invalid_date_time=(v)

Modify the type translators for the date, time, and timestamp types depending on the value given.

[Source]

         # File lib/sequel/adapters/mysql.rb, line 137
    137:       def convert_invalid_date_time=(v)
    138:         m0 = ::Sequel.method(:string_to_time)
    139:         @conversion_procs[11] = (v != false) ?  lambda{|v| convert_date_time(v, &m0)} : m0
    140:         m1 = ::Sequel.method(:string_to_date)
    141:         m = (v != false) ? lambda{|v| convert_date_time(v, &m1)} : m1
    142:         [10, 14].each{|i| @conversion_procs[i] = m}
    143:         m2 = method(:to_application_timestamp)
    144:         m = (v != false) ? lambda{|v| convert_date_time(v, &m2)} : m2
    145:         [7, 12].each{|i| @conversion_procs[i] = m}
    146:         @convert_invalid_date_time = v
    147:       end

convert_tinyint_to_bool=(v)

Modify the type translator used for the tinyint type based on the value given.

[Source]

         # File lib/sequel/adapters/mysql.rb, line 151
    151:       def convert_tinyint_to_bool=(v)
    152:         @conversion_procs[1] = TYPE_TRANSLATOR.method(v ? :boolean : :integer)
    153:         @convert_tinyint_to_bool = v
    154:       end

database_type()

The database type for this database object, the same as the adapter scheme by default. Should be overridden in adapters (especially shared adapters) to be the correct type, so that even if two separate Database objects are using different adapters you can tell that they are using the same database type. Even better, you can tell that two Database objects that are using the same adapter are connecting to different database types (think JDBC or DataObjects).

      Sequel.connect('jdbc:postgres://...').database_type # => :postgres

[Source]

         # File lib/sequel/database/connecting.rb, line 158
    158:     def database_type
    159:       adapter_scheme
    160:     end

disconnect(opts = {})

Disconnects all available connections from the connection pool. Any connections currently in use will not be disconnected. Options:

:servers : | Should be a symbol specifing the server to disconnect from, or an array of symbols to specify multiple servers.

Example:

      DB.disconnect # All servers
      DB.disconnect(:servers=>:server1) # Single server
      DB.disconnect(:servers=>[:server1, :server2]) # Multiple servers

[Source]

         # File lib/sequel/database/connecting.rb, line 172
    172:     def disconnect(opts = {})
    173:       pool.disconnect(opts)
    174:     end

dump_foreign_key_migration(options={})

Dump foreign key constraints for all tables as a migration. This complements the :foreign_keys=>false option to dump_schema_migration. This only dumps the constraints (not the columns) using alter_table/add_foreign_key with an array of columns.

Note that the migration this produces does not have a down block, so you cannot reverse it.

[Source]

        # File lib/sequel/extensions/schema_dumper.rb, line 20
    20:     def dump_foreign_key_migration(options={})
    21:       ts = tables(options)
    22:       "Sequel.migration do\n  change do\n\#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_foreign_keys(t)}.reject{|x| x == ''}.join(\"\\n\\n\").gsub(/^/o, '    ')}\n  end\nend\n"
    23:     end

dump_indexes_migration(options={})

Dump indexes for all tables as a migration. This complements the :indexes=>false option to dump_schema_migration. Options:

:same_db : | Create a dump for the same database type, so don‘t ignore errors if the index statements fail.
:index_names : | If set to false, don‘t record names of indexes. If set to :namespace, prepend the table name to the index name if the database does not use a global index namespace.

[Source]

        # File lib/sequel/extensions/schema_dumper.rb, line 39
    39:     def dump_indexes_migration(options={})
    40:       ts = tables(options)
    41:       "Sequel.migration do\n  change do\n\#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_indexes(t, :add_index, options)}.reject{|x| x == ''}.join(\"\\n\\n\").gsub(/^/o, '    ')}\n  end\nend\n"
    42:     end

dump_schema_cache(file)

Dump the cached schema to the filename given in Marshal format.

[Source]

        # File lib/sequel/extensions/schema_caching.rb, line 52
    52:     def dump_schema_cache(file)
    53:       File.open(file, 'wb'){|f| f.write(Marshal.dump(@schemas))}
    54:       nil
    55:     end

dump_schema_cache?(file)

Dump the cached schema to the filename given unless the file already exists.

[Source]

        # File lib/sequel/extensions/schema_caching.rb, line 59
    59:     def dump_schema_cache?(file)
    60:       dump_schema_cache(file) unless File.exist?(file)
    61:     end

dump_schema_migration(options={})

Return a string that contains a Sequel::Migration subclass that when run would recreate the database structure. Options:

:same_db : | Don‘t attempt to translate database types to ruby types. If this isn‘t set to true, all database types will be translated to ruby types, but there is no guarantee that the migration generated will yield the same type. Without this set, types that aren‘t recognized will be translated to a string-like type.
:foreign_keys : | If set to false, don‘t dump foreign_keys (they can be

                added later via #dump_foreign_key_migration)

:indexes : | If set to false, don‘t dump indexes (they can be added later via dump_index_migration).
:index_names : | If set to false, don‘t record names of indexes. If set to :namespace, prepend the table name to the index name.

[Source]

        # File lib/sequel/extensions/schema_dumper.rb, line 64
    64:     def dump_schema_migration(options={})
    65:       options = options.dup
    66:       if options[:indexes] == false && !options.has_key?(:foreign_keys)
    67:         # Unless foreign_keys option is specifically set, disable if indexes
    68:         # are disabled, as foreign keys that point to non-primary keys rely
    69:         # on unique indexes being created first
    70:         options[:foreign_keys] = false
    71:       end
    72:
    73:       ts = sort_dumped_tables(tables(options), options)
    74:       skipped_fks = if sfk = options[:skipped_foreign_keys]
    75:         # Handle skipped foreign keys by adding them at the end via
    76:         # alter_table/add_foreign_key.  Note that skipped foreign keys
    77:         # probably result in a broken down migration.
    78:         sfka = sfk.sort_by{|table, fks| table.to_s}.map{|table, fks| dump_add_fk_constraints(table, fks.values)}
    79:         sfka.join("\n\n").gsub(/^/o, '    ') unless sfka.empty?
    80:       end
    81:
    82:       "Sequel.migration do\n  change do\n\#{ts.map{|t| dump_table_schema(t, options)}.join(\"\\n\\n\").gsub(/^/o, '    ')}\#{\"\\n    \\n\" if skipped_fks}\#{skipped_fks}\n  end\nend\n"
    83:     end

dump_table_schema(table, options={})

Return a string with a create table block that will recreate the given table‘s schema. Takes the same options as dump_schema_migration.

[Source]

        # File lib/sequel/extensions/schema_dumper.rb, line 94
    94:     def dump_table_schema(table, options={})
    95:       table = table.value.to_s if table.is_a?(SQL::Identifier)
    96:       gen = dump_table_generator(table, options)
    97:       commands = [gen.dump_columns, gen.dump_constraints, gen.dump_indexes].reject{|x| x == ''}.join("\n\n")
    98:       "create_table(#{table.inspect}#{', :ignore_index_errors=>true' if !options[:same_db] && options[:indexes] != false && !gen.indexes.empty?}) do\n#{commands.gsub(/^/o, '  ')}\nend"
    99:     end

each_server(&block)

Yield a new Database instance for every server in the connection pool. Intended for use in sharded environments where there is a need to make schema modifications (DDL queries) on each shard.

      DB.each_server{|db| db.create_table(:users){primary_key :id; String :name}}

[Source]

         # File lib/sequel/database/connecting.rb, line 181
    181:     def each_server(&block)
    182:       servers.each{|s| self.class.connect(server_opts(s), &block)}
    183:     end

execute(sql, opts={}) {|log_yield(sql){stmt.executeQuery(sql)}| ...}

Execute the given SQL. If a block is given, if should be a SELECT statement or something else that returns rows.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 239
    239:       def execute(sql, opts={}, &block)
    240:         return call_sproc(sql, opts, &block) if opts[:sproc]
    241:         return execute_prepared_statement(sql, opts, &block) if [Symbol, Dataset].any?{|c| sql.is_a?(c)}
    242:         synchronize(opts[:server]) do |conn|
    243:           statement(conn) do |stmt|
    244:             if block
    245:               yield log_yield(sql){stmt.executeQuery(sql)}
    246:             else
    247:               case opts[:type]
    248:               when :ddl
    249:                 log_yield(sql){stmt.execute(sql)}
    250:               when :insert
    251:                 log_yield(sql) do
    252:                   if requires_return_generated_keys?
    253:                     stmt.executeUpdate(sql, JavaSQL::Statement.RETURN_GENERATED_KEYS)
    254:                   else
    255:                     stmt.executeUpdate(sql)
    256:                   end
    257:                 end
    258:                 last_insert_id(conn, opts.merge(:stmt=>stmt))
    259:               else
    260:                 log_yield(sql){stmt.executeUpdate(sql)}
    261:               end
    262:             end
    263:           end
    264:         end
    265:       end

execute(sql, opts={}) {|res if block_given?| ...}

Execute the given SQL, yielding a Swift::Result if a block is given.

[Source]

        # File lib/sequel/adapters/swift.rb, line 66
    66:       def execute(sql, opts={})
    67:         synchronize(opts[:server]) do |conn|
    68:           begin
    69:             res = log_yield(sql){conn.execute(sql)}
    70:             yield res if block_given?
    71:             nil
    72:           rescue ::Swift::Error => e
    73:             raise_error(e)
    74:           end
    75:         end
    76:       end

execute(sql, opts={}, &block)

Run the given SQL with the given arguments and yield each row.

[Source]

         # File lib/sequel/adapters/sqlite.rb, line 122
    122:       def execute(sql, opts={}, &block)
    123:         _execute(:select, sql, opts, &block)
    124:       end

execute(sql, opts={}) {|res| ...}

Execute the given SQL. If a block is given, the DataObjects::Reader created is yielded to it. A block should not be provided unless a a SELECT statement is being used (or something else that returns rows). Otherwise, the return value is the insert id if opts[:type] is :insert, or the number of affected rows, otherwise.

[Source]

        # File lib/sequel/adapters/do.rb, line 69
    69:       def execute(sql, opts={})
    70:         synchronize(opts[:server]) do |conn|
    71:           begin
    72:             command = conn.create_command(sql)
    73:             res = log_yield(sql){block_given? ? command.execute_reader : command.execute_non_query}
    74:           rescue ::DataObjects::Error => e
    75:             raise_error(e)
    76:           end
    77:           if block_given?
    78:             begin
    79:               yield(res)
    80:             ensure
    81:              res.close if res
    82:             end
    83:           elsif opts[:type] == :insert
    84:             res.insert_id
    85:           else
    86:             res.affected_rows
    87:           end
    88:         end
    89:       end

execute_ddl(sql, opts={})

Execute the given DDL SQL, which should not return any values or rows.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 270
    270:       def execute_ddl(sql, opts={})
    271:         execute(sql, {:type=>:ddl}.merge(opts))
    272:       end

execute_ddl(sql, opts={})

Drop any prepared statements on the connection when executing DDL. This is because prepared statements lock the table in such a way that you can‘t drop or alter the table while a prepared statement that references it still exists.

[Source]

         # File lib/sequel/adapters/sqlite.rb, line 134
    134:       def execute_ddl(sql, opts={})
    135:         synchronize(opts[:server]) do |conn|
    136:           conn.prepared_statements.values.each{|cps, s| cps.close}
    137:           conn.prepared_statements.clear
    138:           super
    139:         end
    140:       end

execute_dui(sql, opts={})

Run the given SQL with the given arguments and return the number of changed rows.

[Source]

         # File lib/sequel/adapters/sqlite.rb, line 127
    127:       def execute_dui(sql, opts={})
    128:         _execute(:update, sql, opts)
    129:       end

execute_dui(sql, opts={})

Return the number of matched rows when executing a delete/update statement.

[Source]

         # File lib/sequel/adapters/mysql.rb, line 157
    157:       def execute_dui(sql, opts={})
    158:         execute(sql, opts){|c| return affected_rows(c)}
    159:       end

execute_dui(sql, opts={})

Alias for execute

execute_dui(sql, opts={})

Execute the SQL on the this database, returning the number of affected rows.

[Source]

        # File lib/sequel/adapters/do.rb, line 93
    93:       def execute_dui(sql, opts={})
    94:         execute(sql, opts)
    95:       end

execute_dui(sql, opts={})

Execute the SQL on the this database, returning the number of affected rows.

[Source]

        # File lib/sequel/adapters/swift.rb, line 80
    80:       def execute_dui(sql, opts={})
    81:         synchronize(opts[:server]) do |conn|
    82:           begin
    83:             log_yield(sql){conn.execute(sql).affected_rows}
    84:           rescue ::Swift::Error => e
    85:             raise_error(e)
    86:           end
    87:         end
    88:       end

execute_insert(sql, opts={})

Execute the SQL on this database, returning the primary key of the table being inserted to.

[Source]

         # File lib/sequel/adapters/do.rb, line 99
     99:       def execute_insert(sql, opts={})
    100:         execute(sql, opts.merge(:type=>:insert))
    101:       end

execute_insert(sql, opts={})

Execute the given INSERT SQL, returning the last inserted row id.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 276
    276:       def execute_insert(sql, opts={})
    277:         execute(sql, {:type=>:insert}.merge(opts))
    278:       end

execute_insert(sql, opts={})

Return the last inserted id when executing an insert statement.

[Source]

         # File lib/sequel/adapters/mysql.rb, line 162
    162:       def execute_insert(sql, opts={})
    163:         execute(sql, opts){|c| return c.insert_id}
    164:       end

execute_insert(sql, opts={})

Run the given SQL with the given arguments and return the last inserted row id.

[Source]

         # File lib/sequel/adapters/sqlite.rb, line 143
    143:       def execute_insert(sql, opts={})
    144:         _execute(:insert, sql, opts)
    145:       end

execute_insert(sql, opts={})

Execute the SQL on this database, returning the primary key of the table being inserted to.

[Source]

         # File lib/sequel/adapters/swift.rb, line 92
     92:       def execute_insert(sql, opts={})
     93:         synchronize(opts[:server]) do |conn|
     94:           begin
     95:             log_yield(sql){conn.execute(sql).insert_id}
     96:           rescue ::Swift::Error => e
     97:             raise_error(e)
     98:           end
     99:         end
    100:       end

indexes(table, opts={})

Use the JDBC metadata to get the index information for the table.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 281
    281:       def indexes(table, opts={})
    282:         m = output_identifier_meth
    283:         im = input_identifier_meth
    284:         schema, table = schema_and_table(table)
    285:         schema ||= opts[:schema]
    286:         schema = im.call(schema) if schema
    287:         table = im.call(table)
    288:         indexes = {}
    289:         metadata(:getIndexInfo, nil, schema, table, false, true) do |r|
    290:           next unless name = r[:column_name]
    291:           next if respond_to?(:primary_key_index_re, true) and r[:index_name] =~ primary_key_index_re
    292:           i = indexes[m.call(r[:index_name])] ||= {:columns=>[], :unique=>[false, 0].include?(r[:non_unique])}
    293:           i[:columns] << m.call(name)
    294:         end
    295:         indexes
    296:       end

jndi?()

Whether or not JNDI is being used for this connection.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 299
    299:       def jndi?
    300:         !!(uri =~ JNDI_URI_REGEXP)
    301:       end

load_schema_cache(file)

Replace the schema cache with the data from the given file, which should be in Marshal format.

[Source]

        # File lib/sequel/extensions/schema_caching.rb, line 65
    65:     def load_schema_cache(file)
    66:       @schemas = Marshal.load(File.read(file))
    67:       nil
    68:     end

load_schema_cache?(file)

Replace the schema cache with the data from the given file if the file exists.

[Source]

        # File lib/sequel/extensions/schema_caching.rb, line 72
    72:     def load_schema_cache?(file)
    73:       load_schema_cache(file) if File.exist?(file)
    74:     end

query(&block)

Return a dataset modified by the query block

[Source]

        # File lib/sequel/extensions/query.rb, line 12
    12:     def query(&block)
    13:       dataset.query(&block)
    14:     end

remove_servers(*servers)

Dynamically remove existing servers from the connection pool. Intended for use with master/slave or shard configurations where it is useful to remove existing server hosts at runtime.

servers should be symbols or arrays of symbols. If a nonexistent server is specified, it is ignored. If no servers have been specified for this database, no changes are made. If you attempt to remove the :default server, an error will be raised.

      DB.remove_servers(:f1, :f2)

[Source]

         # File lib/sequel/database/connecting.rb, line 195
    195:     def remove_servers(*servers)
    196:       if h = @opts[:servers]
    197:         servers.flatten.each{|s| Sequel.synchronize{h.delete(s)}}
    198:         @pool.remove_servers(servers)
    199:       end
    200:     end

server_version(server=nil)

Return the version of the MySQL server two which we are connecting.

[Source]

         # File lib/sequel/adapters/mysql.rb, line 167
    167:       def server_version(server=nil)
    168:         @server_version ||= (synchronize(server){|conn| conn.server_version if conn.respond_to?(:server_version)} || super)
    169:       end

servers()

An array of servers/shards for this Database object.

      DB.servers # Unsharded: => [:default]
      DB.servers # Sharded:   => [:default, :server1, :server2]

[Source]

         # File lib/sequel/database/connecting.rb, line 206
    206:     def servers
    207:       pool.servers
    208:     end

single_threaded?()

Returns true if the database is using a single-threaded connection pool.

[Source]

         # File lib/sequel/database/connecting.rb, line 211
    211:     def single_threaded?
    212:       @single_threaded
    213:     end

subadapter()

Return the subadapter type for this database, i.e. sqlite3 for do:sqlite3::memory:.

[Source]

         # File lib/sequel/adapters/do.rb, line 105
    105:       def subadapter
    106:         uri.split(":").first
    107:       end

synchronize(server=nil) {|conn| ...}

Acquires a database connection, yielding it to the passed block. This is useful if you want to make sure the same connection is used for all database queries in the block. It is also useful if you want to gain direct access to the underlying connection object if you need to do something Sequel does not natively support.

If a server option is given, acquires a connection for that specific server, instead of the :default server.

      DB.synchronize do |conn|
        ...
      end

[Source]

         # File lib/sequel/database/connecting.rb, line 228
    228:       def synchronize(server=nil)
    229:         @pool.hold(server || :default){|conn| yield conn}
    230:       end

synchronize(server=nil, &block)

[Source]

         # File lib/sequel/database/connecting.rb, line 232
    232:       def synchronize(server=nil, &block)
    233:         @pool.hold(server || :default, &block)
    234:       end

tables(opts={})

All tables in this database

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 304
    304:       def tables(opts={})
    305:         get_tables('TABLE', opts)
    306:       end

test_connection(server=nil)

Attempts to acquire a database connection. Returns true if successful. Will probably raise an Error if unsuccessful. If a server argument is given, attempts to acquire a database connection to the given server/shard.

[Source]

         # File lib/sequel/database/connecting.rb, line 241
    241:     def test_connection(server=nil)
    242:       synchronize(server){|conn|}
    243:       true
    244:     end

to_application_timestamp(s)

Handle Integer and Float arguments, since SQLite can store timestamps as integers and floats.

[Source]

         # File lib/sequel/adapters/sqlite.rb, line 148
    148:       def to_application_timestamp(s)
    149:         case s
    150:         when String
    151:           super
    152:         when Integer
    153:           super(Time.at(s).to_s)
    154:         when Float
    155:           super(DateTime.jd(s).to_s)
    156:         else
    157:           raise Sequel::Error, "unhandled type when converting to : #{s.inspect} (#{s.class.inspect})"
    158:         end
    159:       end

uri(opts={})

Return the DataObjects URI for the Sequel URI, removing the do: prefix.

[Source]

         # File lib/sequel/adapters/do.rb, line 111
    111:       def uri(opts={})
    112:         opts = @opts.merge(opts)
    113:         (opts[:uri] || opts[:url]).sub(/\Ado:/, '')
    114:       end

uri(opts={})

The uri for this connection. You can specify the uri using the :uri, :url, or :database options. You don‘t need to worry about this if you use Sequel.connect with the JDBC connectrion strings.

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 312
    312:       def uri(opts={})
    313:         opts = @opts.merge(opts)
    314:         ur = opts[:uri] || opts[:url] || opts[:database]
    315:         ur =~ /^\Ajdbc:/ ? ur : "jdbc:#{ur}"
    316:       end

views(opts={})

All views in this database

[Source]

         # File lib/sequel/adapters/jdbc.rb, line 319
    319:       def views(opts={})
    320:         get_tables('VIEW', opts)
    321:       end

[Validate]