ActiveRecord::ConnectionAdapters::SchemaStatements

add_column(table_name, column_name, type, options = {})

Adds a new column to the named table. See TableDefinition#column for details of the options you can use.

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 261
261:       def add_column(table_name, column_name, type, options = {})
262:         add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
263:         add_column_options!(add_column_sql, options)
264:         execute(add_column_sql)
265:       end

add_index(table_name, column_name, options = {})

Adds a new index to the table. column_name can be a single Symbol, or an Array of Symbols.

The index will be named after the table and the column name(s), unless you pass :name as an option.

Examples

Creating a simple index

 add_index(:suppliers, :name)

generates

 CREATE INDEX suppliers_name_index ON suppliers(name)

Creating a unique index

 add_index(:accounts, [:branch_id, :party_id], :unique => true)

generates

 CREATE UNIQUE INDEX accounts_branch_id_party_id_index ON accounts(branch_id, party_id)

Creating a named index

 add_index(:accounts, [:branch_id, :party_id], :unique => true, :name => 'by_branch_party')

generates

 CREATE UNIQUE INDEX by_branch_party ON accounts(branch_id, party_id)

Creating an index with specific key length

 add_index(:accounts, :name, :name => 'by_name', :length => 10)

generates

 CREATE INDEX by_name ON accounts(name(10))

 add_index(:accounts, [:name, :surname], :name => 'by_name_surname', :length => {:name => 10, :surname => 15})

generates

 CREATE INDEX by_name_surname ON accounts(name(10), surname(15))

Note: SQLite doesn’t support index length

Creating an index with a sort order (desc or asc, asc is the default)

 add_index(:accounts, [:branch_id, :party_id, :surname], :order => {:branch_id => :desc, :part_id => :asc})

generates

 CREATE INDEX by_branch_desc_party ON accounts(branch_id DESC, party_id ASC, surname)

Note: mysql doesn’t yet support index order (it accepts the syntax but ignores it)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 350
350:       def add_index(table_name, column_name, options = {})
351:         index_name, index_type, index_columns = add_index_options(table_name, column_name, options)
352:         execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{index_columns})"
353:       end

add_timestamps(table_name)

Adds timestamps (created_at and updated_at) columns to the named table.

Examples

 add_timestamps(:suppliers)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 518
518:       def add_timestamps(table_name)
519:         add_column table_name, :created_at, :datetime
520:         add_column table_name, :updated_at, :datetime
521:       end

assume_migrated_upto_version(version, migrations_paths = ActiveRecord::Migrator.migrations_paths)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 446
446:       def assume_migrated_upto_version(version, migrations_paths = ActiveRecord::Migrator.migrations_paths)
447:         migrations_paths = Array.wrap(migrations_paths)
448:         version = version.to_i
449:         sm_table = quote_table_name(ActiveRecord::Migrator.schema_migrations_table_name)
450: 
451:         migrated = select_values("SELECT version FROM #{sm_table}").map { |v| v.to_i }
452:         paths = migrations_paths.map {|p| "#{p}/[0-9]*_*.rb" }
453:         versions = Dir[*paths].map do |filename|
454:           filename.split('/').last.split('_').first.to_i
455:         end
456: 
457:         unless migrated.include?(version)
458:           execute "INSERT INTO #{sm_table} (version) VALUES ('#{version}')"
459:         end
460: 
461:         inserted = Set.new
462:         (versions - migrated).each do |v|
463:           if inserted.include?(v)
464:             raise "Duplicate migration #{v}. Please renumber your migrations to resolve the conflict."
465:           elsif v < version
466:             execute "INSERT INTO #{sm_table} (version) VALUES ('#{v}')"
467:             inserted << v
468:           end
469:         end
470:       end

change_column(table_name, column_name, type, options = {})

Changes the column’s definition according to the new options. See TableDefinition#column for details of the options you can use.

Examples

 change_column(:suppliers, :name, :string, :limit => 80)
 change_column(:accounts, :description, :text)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 289
289:       def change_column(table_name, column_name, type, options = {})
290:         raise NotImplementedError, "change_column is not implemented"
291:       end

change_column_default(table_name, column_name, default)

Sets a new default value for a column.

Examples

 change_column_default(:suppliers, :qualification, 'new')
 change_column_default(:accounts, :authorized, 1)
 change_column_default(:users, :email, nil)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 298
298:       def change_column_default(table_name, column_name, default)
299:         raise NotImplementedError, "change_column_default is not implemented"
300:       end

change_table(table_name, options = {})

A block for changing columns in table.

Example

 # change_table() yields a Table instance
 change_table(:suppliers) do |t|
   t.column :name, :string, :limit => 60
   # Other column alterations here
 end

The options hash can include the following keys:

:bulk: Set this to true to make this a bulk alter query, such as ALTER TABLE `users` ADD COLUMN age INT(11), ADD COLUMN birthdate DATETIME …
Defaults to false.

Examples

Add a column

 change_table(:suppliers) do |t|
   t.column :name, :string, :limit => 60
 end

Add 2 integer columns

 change_table(:suppliers) do |t|
   t.integer :width, :height, :null => false, :default => 0
 end

Add created_at/updated_at columns

 change_table(:suppliers) do |t|
   t.timestamps
 end

Add a foreign key column

 change_table(:suppliers) do |t|
   t.references :company
 end

Creates a company_id(integer) column

Add a polymorphic foreign key column

 change_table(:suppliers) do |t|
   t.belongs_to :company, :polymorphic => true
 end

Creates company_type(varchar) and company_id(integer) columns

Remove a column

 change_table(:suppliers) do |t|
   t.remove :company
 end

Remove several columns

 change_table(:suppliers) do |t|
   t.remove :company_id
   t.remove :width, :height
 end

Remove an index

 change_table(:suppliers) do |t|
   t.remove_index :company_id
 end

See also Table for details on all of the various column transformation

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 237
237:       def change_table(table_name, options = {})
238:         if supports_bulk_alter? && options[:bulk]
239:           recorder = ActiveRecord::Migration::CommandRecorder.new(self)
240:           yield Table.new(table_name, recorder)
241:           bulk_change_table(table_name, recorder.commands)
242:         else
243:           yield Table.new(table_name, self)
244:         end
245:       end

column_exists?(table_name, column_name, type = nil, options = {})

Checks to see if a column exists in a given table.

Examples

 # Check a column exists
 column_exists?(:suppliers, :name)

 # Check a column exists of a particular type
 column_exists?(:suppliers, :name, :string)

 # Check a column exists with a specific definition
 column_exists?(:suppliers, :name, :string, :limit => 100)

Source: show | on GitHub

    # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 69
69:       def column_exists?(table_name, column_name, type = nil, options = {})
70:         columns(table_name).any?{ |c| c.name == column_name.to_s &&
71:                                       (!type                 || c.type == type) &&
72:                                       (!options[:limit]      || c.limit == options[:limit]) &&
73:                                       (!options[:precision]  || c.precision == options[:precision]) &&
74:                                       (!options[:scale]      || c.scale == options[:scale]) }
75:       end

columns(table_name, name = nil)

Returns an array of Column objects for the table specified by table_name. See the concrete implementation for details on the expected parameter values.

Source: show | on GitHub

    # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 56
56:       def columns(table_name, name = nil) end

create_table(table_name, options = {})

Creates a new table with the name table_name. table_name may either be a String or a Symbol.

There are two ways to work with create_table. You can use the block form or the regular form, like this:

Block form

 # create_table() passes a TableDefinition object to the block.
 # This form will not only create the table, but also columns for the
 # table.

 create_table(:suppliers) do |t|
   t.column :name, :string, :limit => 60
   # Other fields here
 end

Block form, with shorthand

 # You can also use the column types as method calls, rather than calling the column method.
 create_table(:suppliers) do |t|
   t.string :name, :limit => 60
   # Other fields here
 end

Regular form

 # Creates a table called 'suppliers' with no columns.
 create_table(:suppliers)
 # Add a column to 'suppliers'.
 add_column(:suppliers, :name, :string, {:limit => 60})

The options hash can include the following keys:

:id: Whether to automatically add a primary key column. Defaults to true. Join tables for has_and_belongs_to_many should set it to false.
:primary_key: The name of the primary key, if one is to be added automatically. Defaults to id. If :id is false this option is ignored.
Also note that this just sets the primary key in the table. You additionally need to configure the primary key in the model via self.primary_key=. Models do NOT auto-detect the primary key from their table definition.
:options: Any extra options you want appended to the table definition.
:temporary: Make a temporary table.
:force: Set to true to drop the table before creating it. Defaults to false.

Examples

Add a backend specific option to the generated SQL (MySQL)

 create_table(:suppliers, :options => 'ENGINE=InnoDB DEFAULT CHARSET=utf8')

generates:

 CREATE TABLE suppliers (
   id int(11) DEFAULT NULL auto_increment PRIMARY KEY
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8

Rename the primary key column

 create_table(:objects, :primary_key => 'guid') do |t|
   t.column :name, :string, :limit => 80
 end

generates:

 CREATE TABLE objects (
   guid int(11) DEFAULT NULL auto_increment PRIMARY KEY,
   name varchar(80)
 )

Do not add a primary key column

 create_table(:categories_suppliers, :id => false) do |t|
   t.column :category_id, :integer
   t.column :supplier_id, :integer
 end

generates:

 CREATE TABLE categories_suppliers (
   category_id int,
   supplier_id int
 )

See also TableDefinition#column for details on how to create columns.

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 156
156:       def create_table(table_name, options = {})
157:         td = table_definition
158:         td.primary_key(options[:primary_key] || Base.get_primary_key(table_name.to_s.singularize)) unless options[:id] == false
159: 
160:         yield td if block_given?
161: 
162:         if options[:force] && table_exists?(table_name)
163:           drop_table(table_name, options)
164:         end
165: 
166:         create_sql = "CREATE#{' TEMPORARY' if options[:temporary]} TABLE "
167:         create_sql << "#{quote_table_name(table_name)} ("
168:         create_sql << td.to_sql
169:         create_sql << ") #{options[:options]}"
170:         execute create_sql
171:       end

distinct(columns, order_by)

SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause. Both PostgreSQL and Oracle overrides this for custom DISTINCT syntax.

  distinct("posts.id", "posts.created_at desc")

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 511
511:       def distinct(columns, order_by)
512:         "DISTINCT #{columns}"
513:       end

drop_table(table_name, options = {})

Drops a table from the database.

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 255
255:       def drop_table(table_name, options = {})
256:         execute "DROP TABLE #{quote_table_name(table_name)}"
257:       end

index_exists?(table_name, column_name, options = {})

Checks to see if an index exists on a table for a given index definition.

Examples

 # Check an index exists
 index_exists?(:suppliers, :company_id)

 # Check an index on multiple columns exists
 index_exists?(:suppliers, [:company_id, :company_type])

 # Check a unique index exists
 index_exists?(:suppliers, :company_id, :unique => true)

 # Check an index with a custom name exists
 index_exists?(:suppliers, :company_id, :name => "idx_company_id"

Source: show | on GitHub

    # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 44
44:       def index_exists?(table_name, column_name, options = {})
45:         column_names = Array.wrap(column_name)
46:         index_name = options.key?(:name) ? options[:name].to_s : index_name(table_name, :column => column_names)
47:         if options[:unique]
48:           indexes(table_name).any?{ |i| i.unique && i.name == index_name }
49:         else
50:           indexes(table_name).any?{ |i| i.name == index_name }
51:         end
52:       end

index_name_exists?(table_name, index_name, default)

Verify the existence of an index with a given name.

The default argument is returned if the underlying implementation does not define the indexes method, as there’s no way to determine the correct answer in that case.

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 403
403:       def index_name_exists?(table_name, index_name, default)
404:         return default unless respond_to?(:indexes)
405:         index_name = index_name.to_s
406:         indexes(table_name).detect { |i| i.name == index_name }
407:       end

initialize_schema_migrations_table()

Should not be called normally, but this operation is non-destructive. The migrations module handles this automatically.

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 422
422:       def initialize_schema_migrations_table
423:         sm_table = ActiveRecord::Migrator.schema_migrations_table_name
424: 
425:         unless table_exists?(sm_table)
426:           create_table(sm_table, :id => false) do |schema_migrations_table|
427:             schema_migrations_table.column :version, :string, :null => false
428:           end
429:           add_index sm_table, :version, :unique => true,
430:             :name => "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}"
431: 
432:           # Backwards-compatibility: if we find schema_info, assume we've
433:           # migrated up to that point:
434:           si_table = Base.table_name_prefix + 'schema_info' + Base.table_name_suffix
435: 
436:           if table_exists?(si_table)
437:             ActiveSupport::Deprecation.warn "Usage of the schema table `#{si_table}` is deprecated. Please switch to using `schema_migrations` table"
438: 
439:             old_version = select_value("SELECT version FROM #{quote_table_name(si_table)}").to_i
440:             assume_migrated_upto_version(old_version)
441:             drop_table(si_table)
442:           end
443:         end
444:       end

native_database_types()

Returns a Hash of mappings from the abstract data types to the native database types. See TableDefinition#column for details on the recognized abstract data types.

Source: show | on GitHub

    # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 10
10:       def native_database_types
11:         {}
12:       end

remove_column(table_name, *column_names)

Removes the column(s) from the table definition.

Examples

 remove_column(:suppliers, :qualification)
 remove_columns(:suppliers, :qualification, :experience)

This method is also aliased as remove_columns

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 271
271:       def remove_column(table_name, *column_names)
272:         if column_names.flatten!
273:           message = 'Passing array to remove_columns is deprecated, please use ' +
274:                     'multiple arguments, like: `remove_columns(:posts, :foo, :bar)`'
275:           ActiveSupport::Deprecation.warn message, caller
276:         end
277: 
278:         columns_for_remove(table_name, *column_names).each do |column_name|
279:           execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{column_name}"
280:         end
281:       end

remove_columns(table_name, *column_names)

Alias for remove_column

remove_index(table_name, options = {})

Remove the given index from the table.

Remove the index_accounts_on_column in the accounts table.

  remove_index :accounts, :column

Remove the index named index_accounts_on_branch_id in the accounts table.

  remove_index :accounts, :column => :branch_id

Remove the index named index_accounts_on_branch_id_and_party_id in the accounts table.

  remove_index :accounts, :column => [:branch_id, :party_id]

Remove the index named by_branch_party in the accounts table.

  remove_index :accounts, :name => :by_branch_party

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 365
365:       def remove_index(table_name, options = {})
366:         remove_index!(table_name, index_name_for_remove(table_name, options))
367:       end

remove_timestamps(table_name)

Removes the timestamp columns (created_at and updated_at) from the table definition.

Examples

 remove_timestamps(:suppliers)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 526
526:       def remove_timestamps(table_name)
527:         remove_column table_name, :updated_at
528:         remove_column table_name, :created_at
529:       end

rename_column(table_name, column_name, new_column_name)

Renames a column.

Example

 rename_column(:suppliers, :description, :name)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 305
305:       def rename_column(table_name, column_name, new_column_name)
306:         raise NotImplementedError, "rename_column is not implemented"
307:       end

rename_index(table_name, old_name, new_name)

Rename an index.

Rename the index_people_on_last_name index to index_users_on_last_name

  rename_index :people, 'index_people_on_last_name', 'index_users_on_last_name'

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 377
377:       def rename_index(table_name, old_name, new_name)
378:         # this is a naive implementation; some DBs may support this more efficiently (Postgres, for instance)
379:         old_index_def = indexes(table_name).detect { |i| i.name == old_name }
380:         return unless old_index_def
381:         remove_index(table_name, :name => old_name)
382:         add_index(table_name, old_index_def.columns, :name => new_name, :unique => old_index_def.unique)
383:       end

rename_table(table_name, new_name)

Renames a table.

Example

 rename_table('octopuses', 'octopi')

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 250
250:       def rename_table(table_name, new_name)
251:         raise NotImplementedError, "rename_table is not implemented"
252:       end

structure_dump()

Returns a string of CREATE TABLE SQL statement(s) for recreating the entire structure of the database.

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 411
411:       def structure_dump
412:       end

table_alias_for(table_name)

Truncates a table alias according to the limits of the current adapter.

Source: show | on GitHub

    # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 15
15:       def table_alias_for(table_name)
16:         table_name[0...table_alias_length].gsub(/\./, '_')
17:       end

table_exists?(table_name)

Checks to see if the table table_name exists on the database.

Example

  table_exists?(:developers)

Source: show | on GitHub

    # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 23
23:       def table_exists?(table_name)
24:         tables.include?(table_name.to_s)
25:       end

add_index_options(table_name, column_name, options = {})

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 561
561:         def add_index_options(table_name, column_name, options = {})
562:           column_names = Array.wrap(column_name)
563:           index_name   = index_name(table_name, :column => column_names)
564: 
565:           if Hash === options # legacy support, since this param was a string
566:             index_type = options[:unique] ? "UNIQUE" : ""
567:             index_name = options[:name].to_s if options.key?(:name)
568:           else
569:             index_type = options
570:           end
571: 
572:           if index_name.length > index_name_length
573:             raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{index_name_length} characters"
574:           end
575:           if index_name_exists?(table_name, index_name, false)
576:             raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' already exists"
577:           end
578:           index_columns = quoted_columns_for_index(column_names, options).join(", ")
579: 
580:           [index_name, index_type, index_columns]
581:         end

add_index_sort_order(option_strings, column_names, options = {})

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 532
532:         def add_index_sort_order(option_strings, column_names, options = {})
533:           if options.is_a?(Hash) && order = options[:order]
534:             case order
535:             when Hash
536:               column_names.each {|name| option_strings[name] += " #{order[name].to_s.upcase}" if order.has_key?(name)}
537:             when String
538:               column_names.each {|name| option_strings[name] += " #{order.upcase}"}
539:             end
540:           end
541: 
542:           return option_strings
543:         end

columns_for_remove(table_name, *column_names)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 593
593:         def columns_for_remove(table_name, *column_names)
594:           column_names = column_names.flatten
595: 
596:           raise ArgumentError.new("You must specify at least one column name. Example: remove_column(:people, :first_name)") if column_names.blank?
597:           column_names.map {|column_name| quote_column_name(column_name) }
598:         end

index_name_for_remove(table_name, options = {})

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 583
583:         def index_name_for_remove(table_name, options = {})
584:           index_name = index_name(table_name, options)
585: 
586:           unless index_name_exists?(table_name, index_name, true)
587:             raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' does not exist"
588:           end
589: 
590:           index_name
591:         end

options_include_default?(options)

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 557
557:         def options_include_default?(options)
558:           options.include?(:default) && !(options[:null] == false && options[:default].nil?)
559:         end

quoted_columns_for_index(column_names, options = {})

Overridden by the mysql adapter for supporting index lengths

Source: show | on GitHub

     # File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 546
546:         def quoted_columns_for_index(column_names, options = {})
547:           option_strings = Hash[column_names.map {|name| [name, '']}]
548: 
549:           # add index sort order if supported
550:           if supports_index_sort_order?
551:             option_strings = add_index_sort_order(option_strings, column_names, options)
552:           end
553: 
554:           column_names.map {|name| quote_column_name(name) + option_strings[name]}
555:         end

Module ActiveRecord::ConnectionAdapters::SchemaStatements

Examples

Creating a simple index

Creating a unique index

Creating a named index

Creating an index with specific key length

Creating an index with a sort order (desc or asc, asc is the default)

Examples

Examples

Examples

Example

Examples

Add a column

Add 2 integer columns

Add created_at/updated_at columns

Add a foreign key column

Add a polymorphic foreign key column

Remove a column

Remove several columns

Remove an index

Examples

Block form

Block form, with shorthand

Regular form

Examples

Add a backend specific option to the generated SQL (MySQL)

Rename the primary key column

Do not add a primary key column

Examples

Examples

Examples

Example

Example

Example