Tutorial 4: ER Diagram

1
Tutorial 4 ER Diagram
2

• Question.
• Complete the diagram to capture the following
  constraints
  
• Each student must take exactly one course.
• Every course must be taken by at least one
  student.
  

3

• Question. Which design is better and why?

4

• Question. What are the differences in the
  following two designs?
  

5

• Question. What are the primary keys for the three
  relationships, respectively?

6

• Question. Complete the following diagram to
  satisfy these constraints
  
• Every director must have directed some movie, but
  not every actor has played in a movie.
  
• Each director/actor may have directed/played in
  multiple movies.
  
• Each movie is directed by a single director.
• Not every movie has a sequel.