CPSC 304 Introduction to Database Systems

Practice ER to Relational questions

Question 1

Figure 1 : E-R Diagram for Question 1

a) Translate the above E-R diagram to relations using the first method on page 83 – i.e., create a relation for each class and sub-class in an ISA hierarchy. 

b) Would you consider using the second method on page 83 (i.e., create a relation only for the sub-classes in the ISA hierarchy) to translate the ISA hierarchy in this diagram?  Why or why not? Note: the reasoning is what matters, not that you get the “right” answer.

Question 2

Consider the following case in music industry:

• An album is released by one or more singers.
• An album needs to be produced by at most one producer.
• Singers promote their new albums with a dinner party in a large hall.

It’s represented in the following E-R diagram:

Figure 3 : E-R Diagram for Question 3

Translate the diagram above to relations by writing the database schema. To represent the ISA hierarchy, use the second method on page 83, i.e., create one relation for each subclass but not the superclass.