如果使用Rails 3在现有数据库中不存在，则创建表

I have a doubt.Suppose i have already created model(i.e-User) in Rails 3 application.Now i will connect my app to other database(lets say SQL Server) instead of my DB(where i have created this model before).That Database where i am going to connect has no "User" table and my app has already User.rb file.Here i need when i will connect to my app to that DB,it will automatically execute the query and create table in that DB.Please check my User migration file given below.I have a doubt.Suppose i have already created m