I'm with Luis. I don't like the normalization on DVD. I'll go one further, there is a movie (Luis used title) and there is the physical DVD itself. These are two separate entities. If you break it down that way, then I think you can still maintain the DVD as a child of Store. But, if you don't break it down that way, then you need a many to many relationship between DVD/Title and Store because any given store can have multiple copies of the same movie. I'm unclear why Rental and Rental Details are split. Notice how you have columns in Employee and in Customer that are the same. When you have people in a database, it's best to just have a Person table because you're pretty likely to have that kind of commonality. Then you break out separate tables for the types of person. Because, after all, an Employee can still be a Customer.