learning classes - need pointer

Hi there - I am slowly converting all of my projects over to a OOP based structure with classes. Now I had a quick question. In my current case, I am trying to create all the generic SQL functions (IE insert, update, delete, etc). Now what I am wondering - what would be the best way to structure the code so that I can accommodate the possibilities for different fields and databases, etc? Is it something that I should just pass to the class? Or would there be a more efficient way to do it? d