Module ActiveRecord::ConnectionAdapters::SchemaStatements
In: vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

Methods

Public Instance methods

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

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 121
121:       def add_column(table_name, column_name, type, options = {})
122:         add_column_sql = "ALTER TABLE #{table_name} ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit])}"
123:         add_column_options!(add_column_sql, options)
124:         execute(add_column_sql)
125:       end

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.

When creating an index on multiple columns, the first column is used as a name for the index. For example, when you specify an index on two columns [+:first+, +:last+], the DBMS creates an index for both columns as well as an index for the first colum +:first+. Using just the first name for this index makes sense, because you will never have to create a singular index with this name.

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)

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 186
186:       def add_index(table_name, column_name, options = {})
187:         column_names = Array(column_name)
188:         index_name   = index_name(table_name, :column => column_names.first)
189: 
190:         if Hash === options # legacy support, since this param was a string
191:           index_type = options[:unique] ? "UNIQUE" : ""
192:           index_name = options[:name] || index_name
193:         else
194:           index_type = options
195:         end
196:         quoted_column_names = column_names.map { |e| quote_column_name(e) }.join(", ")
197:         execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{table_name} (#{quoted_column_names})"
198:       end

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]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 139
139:       def change_column(table_name, column_name, type, options = {})
140:         raise NotImplementedError, "change_column is not implemented"
141:       end

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)

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 149
149:       def change_column_default(table_name, column_name, default)
150:         raise NotImplementedError, "change_column_default is not implemented"
151:       end

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]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 28
28:       def columns(table_name, name = nil) end

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.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 90
 90:       def create_table(name, options = {})
 91:         table_definition = TableDefinition.new(self)
 92:         table_definition.primary_key(options[:primary_key] || "id") unless options[:id] == false
 93: 
 94:         yield table_definition
 95: 
 96:         if options[:force]
 97:           drop_table(name) rescue nil
 98:         end
 99: 
100:         create_sql = "CREATE#{' TEMPORARY' if options[:temporary]} TABLE "
101:         create_sql << "#{name} ("
102:         create_sql << table_definition.to_sql
103:         create_sql << ") #{options[:options]}"
104:         execute create_sql
105:       end

Drops a table from the database.

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 115
115:       def drop_table(name)
116:         execute "DROP TABLE #{name}"
117:       end

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

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 237
237:       def initialize_schema_information
238:         begin
239:           execute "CREATE TABLE #{ActiveRecord::Migrator.schema_info_table_name} (version #{type_to_sql(:integer)})"
240:           execute "INSERT INTO #{ActiveRecord::Migrator.schema_info_table_name} (version) VALUES(0)"
241:         rescue ActiveRecord::StatementInvalid
242:           # Schema has been intialized
243:         end
244:       end

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]

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

Removes the column from the table definition.

Examples
 remove_column(:suppliers, :qualification)

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 130
130:       def remove_column(table_name, column_name)
131:         execute "ALTER TABLE #{table_name} DROP #{quote_column_name(column_name)}"
132:       end

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

You can remove an index on multiple columns by specifying the first column.

  add_index :accounts, [:username, :password]
  remove_index :accounts, :username

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 212
212:       def remove_index(table_name, options = {})
213:         execute "DROP INDEX #{quote_column_name(index_name(table_name, options))} ON #{table_name}"
214:       end

Renames a column.

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

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 156
156:       def rename_column(table_name, column_name, new_column_name)
157:         raise NotImplementedError, "rename_column is not implemented"
158:       end

Renames a table.

Example
 rename_table('octopuses', 'octopi')

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 110
110:       def rename_table(name, new_name)
111:         raise NotImplementedError, "rename_table is not implemented"
112:       end

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

[Source]

     # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 232
232:       def structure_dump
233:       end

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

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 17
17:       def table_alias_for(table_name)
18:         table_name[0..table_alias_length-1].gsub(/\./, '_')
19:       end

This is the maximum length a table alias can be

[Source]

    # File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 12
12:       def table_alias_length
13:         255
14:       end

[Validate]