Support Old Database Schema

Dear friends,

I’m quite new to Yii and I’m not sure what is the proper way to solve the following problem.

My client has an application that will be completely rewritten to support new features and also a better GUI. The database schema needs to be changed and, as the new application is being developed, it should support the old database. This is to allow the users to choose which GUI they want to access until we can completely shutdown the old app.

For example, in the old database I have:

- question {questionID, title, answer, weight}

In the answer column, data is stored as TEXT in the following format:

1: poor

2: average

3: good

In the new database:

- question {questionID, title, weight}

- answer {answerID, questionID, value, label}

The question is: how to develop this system accessing the old database and easily change to the new one in the future? I already have created all the models, views, and controllers considering the new database.

Thank you in advance.