Questão 1
Questão
1. The entity super type contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype.
Questão 2
Questão
2. Entity super types and subtypes are organized in a specialization hierarchy.
Questão 3
Questão
3. The relationships depicted within the specialization hierarchy are sometimes described in terms of “is-a” relationships.
Questão 4
Questão
4. Within a specialization hierarchy, a super type can exist only within the context of a subtype.
Questão 5
Questão
5. One important inheritance characteristic is that all entity subtypes inherit their primary key attribute from their super type.
Questão 6
Questão
6. At the implementation level, the super type and its subtype(s) depicted in the specialization hierarchy maintain a 1:1 relationship.
Questão 7
Questão
7. Entity subtypes do not inherit the relationships in which the super type entity participates.
Questão 8
Questão
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.
Questão 9
Questão
9. The property of subtype discriminator enables an entity super type to inherit the attributes and relationships of the subtype.
Questão 10
Questão
10. An entity super type can have disjoint or overlapping entity subtypes
Questão 11
Questão
11. Disjoint subtypes are subtypes that contain non unique subsets of the super type entity set.
Questão 12
Questão
12. Overlapping subtypes are subtypes that contain a unique subset of the super type entity set
Questão 13
Questão
13. Implementing non-overlapping subtypes requires the use of one discriminator attribute for each subtype.
Questão 14
Questão
14. The completeness constraint can be partial or total.
Questão 15
Questão
15. Specialization is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity super type.
Questão 16
Questão
16. Generalization is based on grouping unique characteristics and relationships of the subtypes.
Questão 17
Questão
17. An entity cluster is a "virtual" entity type used to represent multiple entities and relationships in the ERD.
Questão 18
Questão
18. To model time-variant data, you must create a new entity in a M:N relationship with the original entity.
Questão 19
Questão
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.
Questão 20
Questão
20. Some designs use redundant relationships as a way to simplify the design.