爲什麼遷移沒有時間戳時會創建created_at/updated_at？

Question

我正在使用rails 3.2進行以下遷移，並且created_at/updated_at都生成了。我的印象是添加t.timestamps是造成這些列產生的原因。

class CreateContactsCountries < ActiveRecord::Migration 
    def change 
    create_table :contacts_countries do |t| 
     t.string :name, :official_name, :null => false 
     t.string :alpha_2_code, :null => false, :limit => 2 
     t.string :alpha_3_code, :null => false, :limit => 3 
    end 

    add_index :contacts_countries, :alpha_2_code 
    end 
end 

Answer 1

請刪除表和監守

By default, the generated migration will include t.timestamps (which creates 
the updated_at and created_at columns that are automatically populated 
by Active Record). 

價再次檢查this