In this screencast, we’ll talk about null values, which can tend to sneak into any large application that has been around for some time. We’ll go over our philosophy on data integrity and our thoughts on nulls, and what to do about them in an existing app with null constraints.
We're continuing our look at adding integrity to an already existing database backed web application. In this screencast we will be adding a uniqueness constraint. This is one of the more difficult constraints to add to existing data as you must come up with a way to get rid of duplicates.