No... Say you want to write a function to insert a timestamp into a row and you're dealing with many different backend DBMS's that each do this in their own particular way. So you write a seperate insert_time() method for each DBD you might ever connect to and then in your script just call $dbh->insert_time and DBI would work out which insert_time() method to call depeneding on which DBD the $dbh is using. And these methods can be inherited, so you can have a catchall insert_time() method too.
I hope that explains it Ok. -- Simon Oliver
