I'm trying to refactor my application into MVC, but I'm stuck on the M part.

In a database-backed app, the model is implemented in the app code, right?  

But then, what is in the database -- is that not also the model? 

(I'm not using the database as a simple object store -- the data in the DB is an enterprise asset).

Yea, both the model in the code and database are the "Model".

The model has to do with what your application "IS", and the controller is what it "does".  Any code dealing with direct persistence to the database is considered the Model.

Note: MVC is a pattern, so don't over-think it.  It's easy to get all super into doing MVC the right way, but at the end of the day, it's just a mindset!  It means keep your business logic out of the database and UI - that's it.  Before MVC, people would put business logic all up in their webpages when it should be on the server, or they would have a bunch of scripts firing in the database doing business logic right along with the persistence code.  MVC was brought about to get people to start thinking in a way that helps make their code reusable, so don't get caught up in the details too much.
