Exercise 3.1 Dene the following terms: relation schema, relational database schema, domain, attribute, attribute domain, relation instance, relation cardinality, and relation degree.

Exercise 3.4 What is the difference between a candidate key and the primary key for a given relation? What is a superkey?

Exercise 3.5 Consider the instance of the Students relation shown in Figure 3.1.

1. Give an example of an attribute (or set of attributes) that you can deduce is not a candidate key, based on this instance being legal.

2. Is there any example of an attribute (or set of attributes) that you can deduce is a candidate key, based on this instance being legal?

Exercise 3.6 What is a foreign key constraint? Why are such constraints important?

What is referential integrity?