Chapter 5 Multiple Choice

1. The extended entity relationship model (EERM) is sometimes referred to as the ____.

2. ____ is a generic entity type that is related to one or more entity subtypes.

3. The ____ depicts the arrangement of higher-level entity super types (parent entities) and lower-level entity subtypes (child entities).

4. Within a specialization hierarchy, every subtype can have ____ super type(s) to which it is directly related.

5. A specialization hierarchy can have ____ level(s) of super type/subtype relationships.

6. The property of ____ enables an entity subtype to inherit the attributes and relationships of the super type.

7. One important inheritance characteristic is that all entity subtypes inherit their ____ key attribute from their super type.

8. At the implementation level, the super type and its subtype(s) depicted in the specialization hierarchy maintain a ____ relationship.

9. A(n) ____ is the attribute in the super type entity that determines to which entity subtype each super type occurrence is related.

10. The default comparison condition for the subtype discriminator attribute is the ____ comparison.

11. Non-overlapping subtypes are subtypes that contain a(n) ____ subset of the super type entity set.

12. Overlapping subtypes are subtypes that contain ____ subsets of the super type entity set.

13. Partial completeness is symbolized by ____.

14. ____ is the bottom-up process of identifying a higher-level, more generic entity super type from lower-level entity subtypes.

15. An entity cluster is formed by combining multiple interrelated entities into ____.

16. The most important characteristic of an entity is its ____ key, used to uniquely identify each entity instance.

17. A ____ key is a real-world, generally accepted identifier used to uniquely identify realworld objects.

18. If one exists, a data modeler uses a ____ as the primary key of the entity being modeled.

19. The primary key's main function is to uniquely identify a(n) ____ within a table.

20. Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed only once in the ____relationship.

21. The “____” characteristic of a primary key states the following: The PK must uniquely identify each entity instance. A primary key must be able to guarantee unique values. It cannot contain nulls.

22. The “____” characteristic of a primary key states the following: The selected primary key must not be composed of any attribute(s) that might be considered a security risk or violation. For example, using a Social Security number as a PK in an EMPLOYEE table is not a good idea.

23. The “____” characteristic of a primary key states the following: The PK should not have embedded semantic meaning. An attribute with embedded semantic meaning is probably better used as a descriptive characteristic of the entity rather than as an identifier.

24. Surrogate primary keys are especially helpful when there is no ____ key.

25.____ keys work with primary keys to properly implement relationships in the relational model.

26. The preferred placement for a foreign key when working with a 1:1 relationship is to ____.

27. When selecting a foreign key placement for a 1:1 relationship, place the PK of the entity on the mandatory side in the entity on the optional side as a FK, and make the FK mandatory when ____.

28.____ data refer to data whose values change over time and for which you must keep a history of the data changes.

29. A ____ occurs when you have one entity in two 1:M relationships to other entities, thus producing an association among the other entities that is not expressed in the model.

30.____ relationships occur when there are multiple relationship paths between related entities.

31. According to the data modeling checklist, ____ should clearly define participation and cardinality rules.