Class: Sequel::Database

Inherits:
Object show all
Extended by:
Metaprogramming
Includes:
Metaprogramming
Defined in:
lib/sequel/database.rb,
lib/sequel/database/misc.rb,
lib/sequel/database/query.rb,
lib/sequel/database/dataset.rb,
lib/sequel/database/logging.rb,
lib/sequel/extensions/query.rb,
lib/sequel/database/connecting.rb,
lib/sequel/database/schema_methods.rb,
lib/sequel/extensions/schema_dumper.rb,
lib/sequel/database/dataset_defaults.rb

Overview

A Database object represents a virtual connection to a database. The Database class is meant to be subclassed by database adapters in order to provide the functionality needed for executing queries.

Constant Summary collapse

SQL_BEGIN =

:section: Methods that execute queries and/or return results This methods generally execute SQL code on the database server.

'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
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/
ADAPTERS =

Array of supported database adapters

%w'ado amalgalite db2 dbi do firebird informix jdbc mysql odbc openbase oracle postgres sqlite'.collect{|x| x.to_sym}
AUTOINCREMENT =

:section: Methods that modify the database schema These methods execute code on the database that modifies the database’s schema.

'AUTOINCREMENT'.freeze
CASCADE = 
'CASCADE'.freeze
COMMA_SEPARATOR = 
', '.freeze
NO_ACTION = 
'NO ACTION'.freeze
NOT_NULL = 
' NOT NULL'.freeze
NULL = 
' NULL'.freeze
PRIMARY_KEY = 
' PRIMARY KEY'.freeze
RESTRICT = 
'RESTRICT'.freeze
SET_DEFAULT = 
'SET DEFAULT'.freeze
SET_NULL = 
'SET NULL'.freeze
TEMPORARY = 
'TEMPORARY '.freeze
UNDERSCORE = 
'_'.freeze
UNIQUE = 
' UNIQUE'.freeze
UNSIGNED = 
' UNSIGNED'.freeze
@@single_threaded =

Whether to use the single threaded connection pool by default

false
@@identifier_input_method =

The identifier input method to use by default

nil
@@identifier_output_method =

The identifier output method to use by default

nil
@@quote_identifiers =

Whether to quote identifiers (columns and tables) by default

nil

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Metaprogramming

meta_def

Constructor Details

#initialize(opts = {}, &block) ⇒ Database

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

Sequel::Database is an abstract class that is not useful by itself.

Takes the following options:

  • :default_schema : The default schema to use, should generally be nil

  • :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

  • :loggers : An array of loggers to use.

  • :quote_identifiers : Whether to quote identifiers

  • :single_threaded : Whether to use a single-threaded connection pool

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



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# File 'lib/sequel/database/misc.rb', line 38

def initialize(opts = {}, &block)
  @opts ||= opts
  @opts = connection_pool_default_options.merge(@opts)
  @loggers = Array(@opts[:logger]) + Array(@opts[:loggers])
  self.log_warn_duration = @opts[:log_warn_duration]
  @opts[:disconnection_proc] ||= proc{|conn| disconnect_connection(conn)}
  block ||= proc{|server| connect(server)}
  @opts[:servers] = {} if @opts[:servers].is_a?(String)
  
  @opts[:single_threaded] = @single_threaded = typecast_value_boolean(@opts.fetch(:single_threaded, @@single_threaded))
  @schemas = {}
  @default_schema = @opts.fetch(:default_schema, default_schema_default)
  @prepared_statements = {}
  @transactions = []
  @identifier_input_method = nil
  @identifier_output_method = nil
  @quote_identifiers = nil
  @pool = ConnectionPool.get_pool(@opts, &block)

  ::Sequel::DATABASES.push(self)
end

Instance Attribute Details

#default_schema ⇒ Object

The default schema to use, generally should be nil.



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# File 'lib/sequel/database/dataset_defaults.rb', line 46

def default_schema
  @default_schema
end

#log_warn_duration ⇒ Object

Numeric specifying the duration beyond which queries are logged at warn level instead of info level.



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# File 'lib/sequel/database/logging.rb', line 10

def log_warn_duration
  @log_warn_duration
end

#loggers ⇒ Object

Array of SQL loggers to use for this database



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# File 'lib/sequel/database/logging.rb', line 13

def loggers
  @loggers
end

#opts ⇒ Object (readonly)

The options for this database



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# File 'lib/sequel/database/misc.rb', line 20

def opts
  @opts
end

#pool ⇒ Object (readonly)

The connection pool for this database



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# File 'lib/sequel/database/connecting.rb', line 108

def pool
  @pool
end

#prepared_statements ⇒ Object (readonly)

The prepared statement objects for this database, keyed by name



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# File 'lib/sequel/database/query.rb', line 25

def prepared_statements
  @prepared_statements
end

Class Method Details

.adapter_class(scheme) ⇒ Object

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



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# File 'lib/sequel/database/connecting.rb', line 17

def self.adapter_class(scheme)
  scheme = scheme.to_s.gsub('-', '_').to_sym
  
  unless klass = ADAPTER_MAP[scheme]
    # attempt to load the adapter file
    begin
      Sequel.tsk_require "sequel/adapters/#{scheme}"
    rescue LoadError => e
      raise Sequel.convert_exception_class(e, AdapterNotFound)
    end
    
    # make sure we actually loaded the adapter
    unless klass = ADAPTER_MAP[scheme]
      raise AdapterNotFound, "Could not load #{scheme} adapter"
    end
  end
  klass
end

.adapter_scheme ⇒ Object

Returns the scheme for the Database class.



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# File 'lib/sequel/database/connecting.rb', line 37

def self.adapter_scheme
  @scheme
end

.connect(conn_string, opts = {}) ⇒ Object

Connects to a database. See Sequel.connect.



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# File 'lib/sequel/database/connecting.rb', line 42

def self.connect(conn_string, opts = {})
  case conn_string
  when String
    if match = /\A(jdbc|do):/o.match(conn_string)
      c = adapter_class(match[1].to_sym)
      opts = {:uri=>conn_string}.merge(opts)
    else
      uri = URI.parse(conn_string)
      scheme = uri.scheme
      scheme = :dbi if scheme =~ /\Adbi-/
      c = adapter_class(scheme)
      uri_options = c.send(:uri_to_options, uri)
      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?
      uri_options.entries.each{|k,v| uri_options[k] = URI.unescape(v) if v.is_a?(String)}
      opts = uri_options.merge(opts)
    end
  when Hash
    opts = conn_string.merge(opts)
    c = adapter_class(opts[:adapter] || opts['adapter'])
  else
    raise Error, "Sequel::Database.connect takes either a Hash or a String, given: #{conn_string.inspect}"
  end
  # process opts a bit
  opts = opts.inject({}) do |m, kv| k, v = *kv
    k = :user if k.to_s == 'username'
    m[k.to_sym] = v
    m
  end
  begin
    db = c.new(opts)
    db.test_connection if opts[:test] && db.send(:typecast_value_boolean, opts[:test])
    result = yield(db) if block_given?
  ensure
    if block_given?
      db.disconnect if db
      ::Sequel::DATABASES.delete(db)
    end
  end
  block_given? ? result : db
end

.identifier_input_method ⇒ Object

The method to call on identifiers going into the database



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# File 'lib/sequel/database/dataset_defaults.rb', line 18

def self.identifier_input_method
  @@identifier_input_method
end

.identifier_input_method=(v) ⇒ Object

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



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# File 'lib/sequel/database/dataset_defaults.rb', line 24

def self.identifier_input_method=(v)
  @@identifier_input_method = v || ""
end

.identifier_output_method ⇒ Object

The method to call on identifiers coming from the database



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# File 'lib/sequel/database/dataset_defaults.rb', line 29

def self.identifier_output_method
  @@identifier_output_method
end

.identifier_output_method=(v) ⇒ Object

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



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# File 'lib/sequel/database/dataset_defaults.rb', line 35

def self.identifier_output_method=(v)
  @@identifier_output_method = v || ""
end

.quote_identifiers=(value) ⇒ Object

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



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# File 'lib/sequel/database/dataset_defaults.rb', line 41

def self.quote_identifiers=(value)
  @@quote_identifiers = value
end

.single_threaded=(value) ⇒ Object

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



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# File 'lib/sequel/database/connecting.rb', line 85

def self.single_threaded=(value)
  @@single_threaded = value
end

Instance Method Details

#<<(sql) ⇒ Object

Runs the supplied SQL statement string on the database server. Alias for run.



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# File 'lib/sequel/database/query.rb', line 29

def <<(sql)
  run(sql)
end

#[](*args) ⇒ Object

Returns a dataset from the database. If the first argument is a string, the method acts as an alias for Database#fetch, returning a dataset for arbitrary SQL:

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"



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# File 'lib/sequel/database/dataset.rb', line 18

def [](*args)
  (String === args.first) ? fetch(*args) : from(*args)
end

#add_column(table, *args) ⇒ Object

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.



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# File 'lib/sequel/database/schema_methods.rb', line 30

def add_column(table, *args)
  alter_table(table) {add_column(*args)}
end

#add_index(table, columns, options = {}) ⇒ Object

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.



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# File 'lib/sequel/database/schema_methods.rb', line 44

def add_index(table, columns, options={})
  e = options[:ignore_errors]
  begin
    alter_table(table){add_index(columns, options)}
  rescue DatabaseError
    raise unless e
  end
end

#add_servers(servers) ⇒ Object

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"})



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# File 'lib/sequel/database/connecting.rb', line 119

def add_servers(servers)
  @opts[:servers] = @opts[:servers] ? @opts[:servers].merge(servers) : servers
  @pool.add_servers(servers.keys)
end

#alter_table(name, generator = nil, &block) ⇒ Object

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.



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# File 'lib/sequel/database/schema_methods.rb', line 70

def alter_table(name, generator=nil, &block)
  generator ||= Schema::AlterTableGenerator.new(self, &block)
  alter_table_sql_list(name, generator.operations).flatten.each {|sql| execute_ddl(sql)}
  remove_cached_schema(name)
  nil
end

#call(ps_name, hash = {}) ⇒ Object

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



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# File 'lib/sequel/database/query.rb', line 35

def call(ps_name, hash={})
  prepared_statements[ps_name].call(hash)
end

#cast_type_literal(type) ⇒ Object

Cast the given type to a literal type



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# File 'lib/sequel/database/misc.rb', line 61

def cast_type_literal(type)
  type_literal(:type=>type)
end

#connect(server) ⇒ Object

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

Raises:



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# File 'lib/sequel/database/connecting.rb', line 125

def connect(server)
  raise NotImplemented, "#connect should be overridden by adapters"
end

#create_or_replace_view(name, source) ⇒ Object

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'))



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# File 'lib/sequel/database/schema_methods.rb', line 115

def create_or_replace_view(name, source)
  source = source.sql if source.is_a?(Dataset)
  execute_ddl("CREATE OR REPLACE VIEW #{quote_schema_table(name)} AS #{source}")
  remove_cached_schema(name)
  nil
end

#create_table(name, options = {}, &block) ⇒ Object

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

Options:

  • :temp - Create the table as a temporary table.

  • :ignore_index_errors - Ignore any errors when creating indexes.

See Schema::Generator and the “Migrations and Schema Modification” guide.



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# File 'lib/sequel/database/schema_methods.rb', line 91

def create_table(name, options={}, &block)
  remove_cached_schema(name)
  options = {:generator=>options} if options.is_a?(Schema::Generator)
  generator = options[:generator] || Schema::Generator.new(self, &block)
  create_table_from_generator(name, generator, options)
  create_table_indexes_from_generator(name, generator, options)
  nil
end

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

Forcibly creates a table, attempting to drop it unconditionally (and catching any errors), then creating it.



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# File 'lib/sequel/database/schema_methods.rb', line 101

def create_table!(name, options={}, &block)
  drop_table(name) rescue nil
  create_table(name, options, &block)
end

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

Creates the table unless the table already exists

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/schema_methods.rb', line 107

def create_table?(name, options={}, &block)
  create_table(name, options, &block) unless table_exists?(name)
end

#create_view(name, source) ⇒ Object

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'))



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# File 'lib/sequel/database/schema_methods.rb', line 126

def create_view(name, source)
  source = source.sql if source.is_a?(Dataset)
  execute_ddl("CREATE VIEW #{quote_schema_table(name)} AS #{source}")
end

#database_type ⇒ Object

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).



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# File 'lib/sequel/database/connecting.rb', line 136

def database_type
  self.class.adapter_scheme
end

#dataset ⇒ Object

Returns a blank dataset for this database



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# File 'lib/sequel/database/dataset.rb', line 23

def dataset
  ds = Sequel::Dataset.new(self)
end

#disconnect(opts = {}) ⇒ Object

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.



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# File 'lib/sequel/database/connecting.rb', line 144

def disconnect(opts = {})
  pool.disconnect(opts)
end

#drop_column(table, *args) ⇒ Object

Removes a column from the specified table:

DB.drop_column :items, :category

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 136

def drop_column(table, *args)
  alter_table(table) {drop_column(*args)}
end

#drop_index(table, columns, options = {}) ⇒ Object

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

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

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 146

def drop_index(table, columns, options={})
  alter_table(table){drop_index(columns, options)}
end

#drop_table(*names) ⇒ Object

Drops one or more tables corresponding to the given names:

DB.drop_table(:posts, :comments)



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# File 'lib/sequel/database/schema_methods.rb', line 153

def drop_table(*names)
  names.each do |n|
    execute_ddl(drop_table_sql(n))
    remove_cached_schema(n)
  end
  nil
end

#drop_view(*names) ⇒ Object

Drops one or more views corresponding to the given names:

DB.drop_view(:cheap_items)



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# File 'lib/sequel/database/schema_methods.rb', line 164

def drop_view(*names)
  names.each do |n|
    execute_ddl("DROP VIEW #{quote_schema_table(n)}")
    remove_cached_schema(n)
  end
  nil
end

#dump_indexes_migration(options = {}) ⇒ Object

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.



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# File 'lib/sequel/extensions/schema_dumper.rb', line 13

def dump_indexes_migration(options={})
  ts = tables(options)
  <<END_MIG
Sequel.migration do
  up do
#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_indexes(t, :add_index, options)}.reject{|x| x == ''}.join("\n\n").gsub(/^/o, '    ')}
  end
  
  down do
#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_indexes(t, :drop_index, options)}.reject{|x| x == ''}.join("\n\n").gsub(/^/o, '    ')}
  end
end
END_MIG
end

#dump_schema_migration(options = {}) ⇒ Object

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.

  • :indexes - If set to false, don’t dump indexes (they can be added later via dump_index_migration).



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# File 'lib/sequel/extensions/schema_dumper.rb', line 37

def dump_schema_migration(options={})
  ts = tables(options)
  <<END_MIG
Sequel.migration do
  up do
#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_schema(t, options)}.join("\n\n").gsub(/^/o, '    ')}
  end
  
  down do
drop_table(#{ts.sort_by{|t| t.to_s}.inspect[1...-1]})
  end
end
END_MIG
end

#dump_table_schema(table, options = {}) ⇒ Object

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

Raises:



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# File 'lib/sequel/extensions/schema_dumper.rb', line 54

def dump_table_schema(table, options={})
  table = table.value.to_s if table.is_a?(SQL::Identifier)
  raise(Error, "must provide table as a Symbol, String, or Sequel::SQL::Identifier") unless [String, Symbol].any?{|c| table.is_a?(c)}
  s = schema(table).dup
  pks = s.find_all{|x| x.last[:primary_key] == true}.map{|x| x.first}
  options = options.merge(:single_pk=>true) if pks.length == 1
  m = method(:column_schema_to_generator_opts)
  im = method(:index_to_generator_opts)
  begin
    indexes = indexes(table).sort_by{|k,v| k.to_s} if options[:indexes] != false
  rescue Sequel::NotImplemented
    nil
  end
  gen = Schema::Generator.new(self) do
    s.each{|name, info| send(*m.call(name, info, options))}
    primary_key(pks) if !@primary_key && pks.length > 0
    indexes.each{|iname, iopts| send(:index, iopts[:columns], im.call(table, iname, iopts))} if indexes
  end
  commands = [gen.dump_columns, gen.dump_constraints, gen.dump_indexes].reject{|x| x == ''}.join("\n\n")
  "create_table(#{table.inspect}#{', :ignore_index_errors=>true' if !options[:same_db] && options[:indexes] != false && indexes && !indexes.empty?}) do\n#{commands.gsub(/^/o, '  ')}\nend"
end

#each_server(&block) ⇒ Object

Yield a new database object 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}}



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# File 'lib/sequel/database/connecting.rb', line 153

def each_server(&block)
  servers.each{|s| self.class.connect(server_opts(s), &block)}
end

#execute(sql, opts = {}) ⇒ Object

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

Raises:



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# File 'lib/sequel/database/query.rb', line 41

def execute(sql, opts={})
  raise NotImplemented, "#execute should be overridden by adapters"
end

#execute_ddl(sql, opts = {}, &block) ⇒ Object

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



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# File 'lib/sequel/database/query.rb', line 48

def execute_ddl(sql, opts={}, &block)
  execute_dui(sql, opts, &block)
end

#execute_dui(sql, opts = {}, &block) ⇒ Object

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.



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# File 'lib/sequel/database/query.rb', line 55

def execute_dui(sql, opts={}, &block)
  execute(sql, opts, &block)
end

#execute_insert(sql, opts = {}, &block) ⇒ Object

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.



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# File 'lib/sequel/database/query.rb', line 62

def execute_insert(sql, opts={}, &block)
  execute_dui(sql, opts, &block)
end

#fetch(sql, *args, &block) ⇒ Object

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 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



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# File 'lib/sequel/database/dataset.rb', line 40

def fetch(sql, *args, &block)
  ds = dataset.with_sql(sql, *args)
  ds.each(&block) if block
  ds
end

#from(*args, &block) ⇒ Object

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



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# File 'lib/sequel/database/dataset.rb', line 48

def from(*args, &block)
  ds = dataset.from(*args)
  block ? ds.filter(&block) : ds
end

#get(*args, &block) ⇒ Object

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

# SELECT 1
DB.get(1) #=> 1 

# SELECT version()
DB.get(:version.sql_function) #=> ...



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# File 'lib/sequel/database/query.rb', line 73

def get(*args, &block)
  dataset.get(*args, &block)
end

#identifier_input_method ⇒ Object

The method to call on identifiers going into the database



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# File 'lib/sequel/database/dataset_defaults.rb', line 49

def identifier_input_method
  case @identifier_input_method
  when nil
    @identifier_input_method = @opts.fetch(:identifier_input_method, (@@identifier_input_method.nil? ? identifier_input_method_default : @@identifier_input_method))
    @identifier_input_method == "" ? nil : @identifier_input_method
  when ""
    nil
  else
    @identifier_input_method
  end
end

#identifier_input_method=(v) ⇒ Object

Set the method to call on identifiers going into the database



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# File 'lib/sequel/database/dataset_defaults.rb', line 62

def identifier_input_method=(v)
  reset_schema_utility_dataset
  @identifier_input_method = v || ""
end

#identifier_output_method ⇒ Object

The method to call on identifiers coming from the database



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# File 'lib/sequel/database/dataset_defaults.rb', line 68

def identifier_output_method
  case @identifier_output_method
  when nil
    @identifier_output_method = @opts.fetch(:identifier_output_method, (@@identifier_output_method.nil? ? identifier_output_method_default : @@identifier_output_method))
    @identifier_output_method == "" ? nil : @identifier_output_method
  when ""
    nil
  else
    @identifier_output_method
  end
end

#identifier_output_method=(v) ⇒ Object

Set the method to call on identifiers coming from the database



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# File 'lib/sequel/database/dataset_defaults.rb', line 81

def identifier_output_method=(v)
  reset_schema_utility_dataset
  @identifier_output_method = v || ""
end

#indexes(table, opts = {}) ⇒ Object

Return a hash containing index information. 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.

Raises:



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# File 'lib/sequel/database/query.rb', line 83

def indexes(table, opts={})
  raise NotImplemented, "#indexes should be overridden by adapters"
end

#inspect ⇒ Object

Returns a string representation of the database object including the class name and the connection URI (or the opts if the URI cannot be constructed).



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# File 'lib/sequel/database/misc.rb', line 68

def inspect
  "#<#{self.class}: #{(uri rescue opts).inspect}>" 
end

#literal(v) ⇒ Object

Proxy the literal call to the dataset, used for default values.



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# File 'lib/sequel/database/misc.rb', line 73

def literal(v)
  schema_utility_dataset.literal(v)
end

#log_info(message, args = nil) ⇒ Object

Log a message at level info to all loggers.



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# File 'lib/sequel/database/logging.rb', line 16

def log_info(message, args=nil)
  log_each(:info, args ? "#{message}; #{args.inspect}" : message)
end

#log_yield(sql, args = nil) ⇒ Object

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.



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# File 'lib/sequel/database/logging.rb', line 22

def log_yield(sql, args=nil)
  return yield if @loggers.empty?
  sql = "#{sql}; #{args.inspect}" if args
  start = Time.now
  begin
    yield
  rescue => e
    log_each(:error, "#{e.class}: #{e.message.strip}: #{sql}")
    raise
  ensure
    log_duration(Time.now - start, sql) unless e
  end
end

#logger=(logger) ⇒ Object

Remove any existing loggers and just use the given logger.



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# File 'lib/sequel/database/logging.rb', line 37

def logger=(logger)
  @loggers = Array(logger)
end

#query(&block) ⇒ Object

Return a dataset modified by the query block



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# File 'lib/sequel/extensions/query.rb', line 8

def query(&block)
  dataset.query(&block)
end

#quote_identifiers=(v) ⇒ Object

Whether to quote identifiers (columns and tables) for this database



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# File 'lib/sequel/database/dataset_defaults.rb', line 87

def quote_identifiers=(v)
  reset_schema_utility_dataset
  @quote_identifiers = v
end

#quote_identifiers? ⇒ Boolean

Returns true if the database quotes identifiers.

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/dataset_defaults.rb', line 93

def quote_identifiers?
  return @quote_identifiers unless @quote_identifiers.nil?
  @quote_identifiers = @opts.fetch(:quote_identifiers, (@@quote_identifiers.nil? ? quote_identifiers_default : @@quote_identifiers))
end

#remove_servers(*servers) ⇒ Object

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)



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# File 'lib/sequel/database/connecting.rb', line 167

def remove_servers(*servers)
  if @opts[:servers] && !@opts[:servers].empty?
    servs = @opts[:servers].dup
    servers.flatten!
    servers.each{|s| servs.delete(s)}
    @opts[:servers] = servs
    @pool.remove_servers(servers)
  end
end

#rename_column(table, *args) ⇒ Object

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.



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# File 'lib/sequel/database/schema_methods.rb', line 189

def rename_column(table, *args)
  alter_table(table) {rename_column(*args)}
end

#rename_table(name, new_name) ⇒ Object

Renames a table:

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



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# File 'lib/sequel/database/schema_methods.rb', line 177

def rename_table(name, new_name)
  execute_ddl(rename_table_sql(name, new_name))
  remove_cached_schema(name)
  nil
end

#run(sql, opts = {}) ⇒ Object

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

  • :server - The server to run the SQL on.



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# File 'lib/sequel/database/query.rb', line 90

def run(sql, opts={})
  execute_ddl(sql, opts)
  nil
end

#schema(table, opts = {}) ⇒ Object

Parse the schema from the database. 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. Available options are:

  • :reload - Get fresh information from the database, instead of using cached information. If table_name is blank, :reload should be used unless you are sure that schema has not been called before with a table_name, otherwise you may only getting the schemas for tables that have been requested explicitly.

  • :schema - An explicit schema to use. It may also be implicitly provided via the table name.

Raises:



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# File 'lib/sequel/database/query.rb', line 107

def schema(table, opts={})
  raise(Error, 'schema parsing is not implemented on this database') unless respond_to?(:schema_parse_table, true)

  sch, table_name = schema_and_table(table)
  quoted_name = quote_schema_table(table)
  opts = opts.merge(:schema=>sch) if sch && !opts.include?(:schema)

  @schemas.delete(quoted_name) if opts[:reload]
  return @schemas[quoted_name] if @schemas[quoted_name]

  cols = schema_parse_table(table_name, opts)
  raise(Error, 'schema parsing returned no columns, table probably doesn\'t exist') if cols.nil? || cols.empty?
  cols.each{|_,c| c[:ruby_default] = column_schema_to_ruby_default(c[:default], c[:type])}
  @schemas[quoted_name] = cols
end

#select(*args, &block) ⇒ Object

Returns a new dataset with the select method invoked.



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# File 'lib/sequel/database/dataset.rb', line 54

def select(*args, &block)
  dataset.select(*args, &block)
end

#serial_primary_key_options ⇒ Object

Default serial primary key options.



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# File 'lib/sequel/database/misc.rb', line 78

def serial_primary_key_options
  {:primary_key => true, :type => Integer, :auto_increment => true}
end

#servers ⇒ Object

An array of servers/shards for this Database object.



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# File 'lib/sequel/database/connecting.rb', line 178

def servers
  pool.servers
end

#set_column_default(table, *args) ⇒ Object

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

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

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 198

def set_column_default(table, *args)
  alter_table(table) {set_column_default(*args)}
end

#set_column_type(table, *args) ⇒ Object

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

DB.set_column_type :items, :price, :float

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 207

def set_column_type(table, *args)
  alter_table(table) {set_column_type(*args)}
end

#single_threaded? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/connecting.rb', line 183

def single_threaded?
  @single_threaded
end

#supports_savepoints? ⇒ Boolean

Whether the database and adapter support savepoints, false by default

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/misc.rb', line 83

def supports_savepoints?
  false
end

#synchronize(server = nil, &block) ⇒ Object

Acquires a database connection, yielding it to the passed block.



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# File 'lib/sequel/database/connecting.rb', line 188

def synchronize(server=nil, &block)
  @pool.hold(server || :default, &block)
end

#table_exists?(name) ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/query.rb', line 125

def table_exists?(name)
  begin 
    from(name).first
    true
  rescue
    false
  end
end

#tables(opts = {}) ⇒ Object

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

Raises:



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# File 'lib/sequel/database/query.rb', line 135

def tables(opts={})
  raise NotImplemented, "#tables should be overridden by adapters"
end

#test_connection(server = nil) ⇒ Object

Attempts to acquire a database connection. Returns true if successful. Will probably raise an error if unsuccessful.



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# File 'lib/sequel/database/connecting.rb', line 194

def test_connection(server=nil)
  synchronize(server){|conn|}
  true
end

#transaction(opts = {}, &block) ⇒ Object

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 options are respected:

  • :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.



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# File 'lib/sequel/database/query.rb', line 150

def transaction(opts={}, &block)
  synchronize(opts[:server]) do |conn|
    return yield(conn) if already_in_transaction?(conn, opts)
    _transaction(conn, &block)
  end
end

#typecast_value(column_type, value) ⇒ Object

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.



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# File 'lib/sequel/database/misc.rb', line 92

def typecast_value(column_type, value)
  return nil if value.nil?
  meth = "typecast_value_#{column_type}"
  begin
    respond_to?(meth, true) ? send(meth, value) : value
  rescue ArgumentError, TypeError => e
    raise Sequel.convert_exception_class(e, InvalidValue)
  end
end

#uri ⇒ Object

Returns the URI identifying the database. This method can raise an error if the database used options instead of a connection string.



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# File 'lib/sequel/database/misc.rb', line 105

def uri
  uri = URI::Generic.new(
    self.class.adapter_scheme.to_s,
    nil,
    @opts[:host],
    @opts[:port],
    nil,
    "/#{@opts[:database]}",
    nil,
    nil,
    nil
  )
  uri.user = @opts[:user]
  uri.password = @opts[:password] if uri.user
  uri.to_s
end

#url ⇒ Object

Explicit alias of uri for easier subclassing.



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# File 'lib/sequel/database/misc.rb', line 123

def url
  uri
end