There are some problems with these entity types.
- Actor and Crew are similar, representing people who work on movies.
- There is therefore likely to be duplication of attributes.
- Some people work in multiple capacities, sometimes on the same
movie. E.g. in Reservoir Dogs, Quentin Tarantino is:
- Director
- A writer
- An actor, playing the role of Mr. Brown
If we keep Actor and Crew as separate entities,
then Quentin is in the database twice. This is not good.
- Bad modeling because the model is inconsistent with the real world.
- Different entity types implies different entities. Difficult
to get the entire picture of one person.
- Redundancy → inconsistency. E.g. different names, different
birth dates, etc.
- Queries get complicated. Have to remember to look for people
in both entity sets.