I actually avoid that, if I may guess at what exactly you mean. If I were to go down that road then I'd want an interface that lets me build queries with methods like select() and where() and join() and such. Otherwise I'll be hard-coding SQL queries, and since all the flavors are different I'd stay away from the good pattern just so that it's more likely to be a problem in the future. Yes, I know it's weird, but if the problem is to arise I'd want it to sooner rather than later.
Yeah, I completely agree, but didn't want really to dump all that on someone just starting out as well. I guess I was just trying at least point out that you should try avoid having your objects depend on hard coded extensions and that instead you should try and have them rely on an interface.
If I had more time I'd like to create an example but really, even for a Saturday, I'm flat out.