I'm a newbie in YII framework. But after exploring the framework. I can conclude that is coolest framework of PHP. :)
In YII all DB tables can be represented by a model class. Where you can set rule and restrict some table column.
One thing I impress of YII is there Active Record feature. Instead of declaring the sql command to query the data of two or more tables. In YII we can just create relation function in the model class to join the tables by assigning the foreign keys.
see details here http://www.yiiframework.com/doc/guide/1.1/en/database.arr