Reading EER Diagrams
Part 1¶
Consider the EER model below and answer the questions, explaining how you got the answers from the diagram notation.
- What are all the attributes of a Y?
- What is the unique identifier of a W?
- True or False: Whatever jumps over an F is either a Y or a Z.
- Identify the multi-valued attribute in the diagram and explain what it tells us.
- True or False: An R may be visited by something that does not jump over an F.
- What are the minimum and maximum number of Y’s an R may be visited by?
Part 2¶
Consider the ER model below and write everything that you know based on reading the model. Use just plain, regular language—do not use any technical terminology like weak entity, or mandatory relationship. Two facts are already written as an example.
- An X is uniquely identified by its XID.
- An X owns at least one Y.