手动操作:

add_column :post, :author_id, :integer

但是现在，当你创建belongs_to语句时，你将不得不修改它，所以现在你必须调用

but now, when you create the belongs_to statement, you will have to modify it, so now you have to call

def post
    belongs_to :user, :foreign_key => 'author_id'
end