change_table

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

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

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 227
      def change_table(table_name)
        yield Table.new(table_name, self)
      end