use "IF NOT EXISTS" in createTable()?

Would it be a good idea to extend the createTable() method to include "IF NOT EXISTS" to avoid errors.

I got into this issue only during development, in cases when I migrate down without removing certain tables, then migrate up, and Yii complains. You might want to check out Yii 1.1.7, Yii supports transaction during migration at 1.1.7 it solves this issue, at least for me.