Migrations in Rails 2.1

Migrations in Rails 2.1
有跑過的migration, 會紀錄在schema_migrations 裡
強化了一些change column的功能
<br /># in a migration file<br />def self.up<br /> change_table :products do |t|<br /> t.rename :released_on, :released_at<br /> t.change :description, :text, :limit => nil, :null => true<br /> t.remove :price<br /> t.integer :stock_quantity<br /> end<br />end<br /><br />def self.down<br /> change_table :products do |t|<br /> t.rename :released_at, :released_on<br /> t.change :description, :string, :null => false<br /> t.decimal :price, :precision => 10, :scale => 2<br /> t.remove :stock_quantity<br /> end<br />end<br />