class design question

hi there. i am working out the finishing touches on a authentication class that uses mysql to store the time of last access and some other goodies. my question is, when developing a class that uses a database, what is the best way to handle the database bit? for now i just set the connection in an .inc file and include that in the class, but there has got to be a better way - especially for portability sake. thanks for any suggestions. - rogue