question of Object

Hi, i have a good question on objects. I have the fallowing classes Page, Elements,Menu,Product , Var (containt the post, get, session...) , Db and Error Page is created once, and i beleive that Db should be created once too. But at the moment it is created in every class that needs to execute a query. I dont find it too nice to do aggregation inside of every class. So i would like to put this Class on a higher level. Avisouly i dont want to do Db to extend all the classes because it would not be to pretty either. Plus using globals,... hummm So is there a way to do what i am looking for without using globals and having Db extend every class that do a connection to the Database ? Thanks Yann Larrivee