Chapter 5 (True/False)

Question 1

1. The entity super type contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype.

Answer

true

Question 2

2. Entity super types and subtypes are organized in a specialization hierarchy.

Answer

true

Question 3

3. The relationships depicted within the specialization hierarchy are sometimes described in terms of “is-a” relationships.

Answer

true

Question 4

4. Within a specialization hierarchy, a super type can exist only within the context of a subtype.

Answer

true

Question 5

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

Answer

true

Question 6

6. At the implementation level, the super type and its subtype(s) depicted in the specialization hierarchy maintain a 1:1 relationship.

Answer

true

Question 7

7. Entity subtypes do not inherit the relationships in which the super type entity participates.

Answer

true

Question 8

8. In specialization hierarchies with multiple levels of super type/subtypes, a lower-level super type inherits all of the attributes and relationships from all of its upper-level subtypes.

Answer

true

Question 9

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

Answer

true

Question 10

10. An entity super type can have disjoint or overlapping entity subtypes

Answer

true

Question 11

11. Disjoint subtypes are subtypes that contain non unique subsets of the super type entity set.

Answer

true

Question 12

12. Overlapping subtypes are subtypes that contain a unique subset of the super type entity set

Answer

true

Question 13

13. Implementing non-overlapping subtypes requires the use of one discriminator attribute for each subtype.

Answer

true

Question 14

14. The completeness constraint can be partial or total.

Answer

true

Question 15

15. Specialization is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity super type.

Answer

true

Question 16

16. Generalization is based on grouping unique characteristics and relationships of the subtypes.

Answer

true

Question 17

17. An entity cluster is a "virtual" entity type used to represent multiple entities and relationships in the ERD.

Answer

true

Question 18

18. To model time-variant data, you must create a new entity in a M:N relationship with the original entity.

Answer

true

Question 19

19. A design trap occurs when a relationship is improperly or incompletely identified and is therefore represented in a way that is not consistent with the real world.

Answer

true

Question 20

20. Some designs use redundant relationships as a way to simplify the design.

Answer

true

Chapter 5 (True/False)

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