Methods
Public Instance methods
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.

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 111
111:       def add_column(table_name, column_name, type, options = {})
112:         add_column_sql = "ALTER TABLE #{table_name} ADD #{column_name} #{type_to_sql(type, options[:limit])}"
113:         add_column_options!(add_column_sql, options)
114:         execute(add_column_sql)
115:       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 first column names, 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_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)

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 169
169:       def add_index(table_name, column_name, options = {})
170:         index_name = "#{table_name}_#{Array(column_name).first}_index"
171: 
172:         if Hash === options # legacy support, since this param was a string
173:           index_type = options[:unique] ? "UNIQUE" : ""
174:           index_name = options[:name] || index_name
175:         else
176:           index_type = options
177:         end
178: 
179:         execute "CREATE #{index_type} INDEX #{index_name} ON #{table_name} (#{Array(column_name).join(", ")})"
180:       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)

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 129
129:       def change_column(table_name, column_name, type, options = {})
130:         raise NotImplementedError, "change_column is not implemented"
131:       end
change_column_default(table_name, column_name, default)

Sets a new default value for a column. If you want to set the default value to NULL, you are out of luck. You need to DatabaseStatements#execute the apppropriate SQL statement yourself.

Examples
 change_column_default(:suppliers, :qualification, 'new')
 change_column_default(:accounts, :authorized, 1)

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 139
139:       def change_column_default(table_name, column_name, default)
140:         raise NotImplementedError, "change_column_default is not implemented"
141:       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.

[ show source ]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 18
18:       def columns(table_name, name = nil) end
create_table(name, options = {}) {|table_definition| ...}

Creates a new table 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() yields a TableDefinition instance
 create_table(:suppliers) do |t|
   t.column :name, :string, :limit => 60
   # Other fields here
 end

Regular form

 create_table(:suppliers)
 add_column(:suppliers, :name, :string, {:limit => 60})

The options hash can include the following keys:

:id
Set to true or false to add/not add a primary key column automatically. Defaults to true.
:primary_key
The name of the primary key, if one is to be added automatically. Defaults to id.
:options
Any extra options you want appended to the table definition.
:temporary
Make a temporary table.
:force
Set to true or false 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_join (
   category_id int,
   supplier_id int
 )

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

[ show source ]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 80
80:       def create_table(name, options = {})
81:         table_definition = TableDefinition.new(self)
82:         table_definition.primary_key(options[:primary_key] || "id") unless options[:id] == false
83: 
84:         yield table_definition
85: 
86:         if options[:force]
87:           drop_table(name) rescue nil
88:         end
89: 
90:         create_sql = "CREATE#{' TEMPORARY' if options[:temporary]} TABLE "
91:         create_sql << "#{name} ("
92:         create_sql << table_definition.to_sql
93:         create_sql << ") #{options[:options]}"
94:         execute create_sql
95:       end
drop_table(name)

Drops a table from the database.

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 105
105:       def drop_table(name)
106:         execute "DROP TABLE #{name}"
107:       end
initialize_schema_information()

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

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 216
216:       def initialize_schema_information
217:         begin
218:           execute "CREATE TABLE #{ActiveRecord::Migrator.schema_info_table_name} (version #{type_to_sql(:integer)})"
219:           execute "INSERT INTO #{ActiveRecord::Migrator.schema_info_table_name} (version) VALUES(0)"
220:         rescue ActiveRecord::StatementInvalid
221:           # Schema has been intialized
222:         end
223:       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.

[ show source ]

   # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 7
7:       def native_database_types
8:         {}
9:       end
remove_column(table_name, column_name)

Removes the column from the table definition.

Examples
 remove_column(:suppliers, :qualification)

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 120
120:       def remove_column(table_name, column_name)
121:         execute "ALTER TABLE #{table_name} DROP #{column_name}"
122:       end
remove_index(table_name, options = {})

Remove the given index from the table.

Remove the suppliers_name_index in the suppliers table (legacy support, use the second or third forms). 

  remove_index :suppliers, :name

Remove the index named accounts_branch_id in the accounts table. 

  remove_index :accounts, :column => :branch_id

Remove the index named by_branch_party in the accounts table. 

  remove_index :accounts, :name => :by_branch_party

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 191
191:       def remove_index(table_name, options = {})
192:         execute "DROP INDEX #{index_name(table_name, options)} ON #{table_name}"
193:       end
rename_column(table_name, column_name, new_column_name)

Renames a column.

Example
 rename_column(:suppliers, :description, :name)

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 146
146:       def rename_column(table_name, column_name, new_column_name)
147:         raise NotImplementedError, "rename_column is not implemented"
148:       end
rename_table(name, new_name)

Renames a table.

Example
 rename_table('octopuses', 'octopi')

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 100
100:       def rename_table(name, new_name)
101:         raise NotImplementedError, "rename_table is not implemented"
102:       end
structure_dump()

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

[ show source ]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 211
211:       def structure_dump
212:       end