If you create your database schema straight from your class structure, then you are probably going to have problems, I think that's pretty much a given. But if

If you create your database schema straight from your class structure, then you are probably going to have problems, I think that's pretty much a given. But if you want to query from an ORM to a reasonably normalized database, then with a bit of thought, you can almost certainly dodge many of the traps that an ORM can lead the unwary.