Exercises from the Book 'Learning MySQL' by Tahaghoghi and Williams
Submitted by: Mike Murphy, Nov 2012

1. When would you use a weak entity?

For an entity that is completely dependent on another entity, you can save space by associating it with the stronger entity, rather than identifying it independently. It can be identified only within the context of that stronger entity.

2. Is it better to use entities instead of attributes?

Items of direct interest to the database, items with components of their own, objects with multiple instances, objects often nonexistent/unknown should be entities, not attributes.

3. Alter and extend the music database ER model so that it can store compilations (1 album, multiple artists)

ER Diagram

4. Create an ER diagram for an online media store using the following requirements:

ER Diagram