I want to talk a little about database design patterns. When working with a relational database, there are a couple of patterns that exist to help you normalize your data. I think one of the most useful patterns in this is the supertype-subtype relationship.
You don’t see a supertype-subtype relationship defined as such when you’re looking at the physical database. You’ll only see it explicitly in the logical data model. So what is the pattern and how do you know that you have one in your database?