References to sources (informal)

1. Describe the characteristics a table must have to be considered a relation.

2. Define the term domain, and explain the significance of the domain integrity constraint to a relation.

3. Using EAR notation to define its entity, give an original example of a table that is not a proper relation. Explain what makes it not a relation.

4. Under what circumstances can a relation have duplicate rows?

5. Define the term non-unique key and give an original example with non-unique keys, using EAR notation to define its entity.

6. Give an original example of a relation with a unique composite key, using EAR notation to define its entity.

7. What is a surrogate key, and under what circumstances would you use one?

8. Why are the values of surrogate keys often hidden from users on forms, queries, and reports?

9. Explain the term foreign key and give an original example, using EAR notation to define its entity.

10. Define the term referential integrity constraint and give an original example of one.

11. How does a referential integrity constraint contribute to database integrity?