to try to be a little clearer - I meant swap amongst MySql/Oracle/SQLServer/whatever. It seems that this was (still is?) one of the purported advantages of an ORM in general, and I was just curious how often it really even comes into play.
This usually comes with a hit to performance though. Raw queries are generally quite a bit faster. So if you dont plan on changing databases on a project, it might be beneficial to skip the ORM where possible.
The ORM also doesnt help you with migrating the records from one database type to another. So if you already have established records that is a separate issue.