Oren has been saying that he completely disagrees with Stephen Forte's assertion that database models support more than one application. Well, he's right and he's wrong.  He's right in that data models (and especially database models) can and should be private to the application.  In practice, they never are.  There's always someone adding a "quick fix" piece of functionality on the side.  Let's look at the main categories: Importing data into the system.  (Including data entry systems.) Adding a separate program e.g. Invoicing added to a tracking system ...