 Show Chapter 05: Advanced Data Modeling True / False 1. The entity supertype contains common characteristics, and the entity subtypes each contain their own unique characteristics. a. True b. Fals e ANSWER: True DIFFICULTY: Difficulty: Easy REFERENCES: 5-1a Entity Supertypes and Subtypes LEARNING OBJ ECTIVES: 05.01 - Describe the main extended entity relationship (EER) model constructs and how they are represented in ERDs and EERDs 2. Entity supertypes and subtypes are organized in a specialization hierarchy. a. True b. Fals e ANSWER: True DIFFICULTY: Difficulty: Easy REFERENCES: 5-1b Specialization Hierarchy LEARNING OBJ ECTIVES: 05.01 - Describe the main extended entity relationship (EER) model constructs and how they are represented in ERDs and EERDs 3. The relationships depicted within the specialization hierarchy are sometimes described in terms of “is-a” relationships. a. True b. Fals e ANSWER: True DIFFICULTY: Difficulty: Moderate REFERENCES: 5-1b Specialization Hierarchy LEARNING OBJ ECTIVES: 05.01 - Describe the main extended entity relationship (EER) model constructs and how they are represented in ERDs and EERDs 4. Within a specialization hierarchy, a supertype can exist only within the context of a subtype. a. True b. Fals e ANSWER: False DIFFICULTY: Difficulty: Easy REFERENCES: 5-1b Specialization Hierarchy LEARNING OBJ ECTIVES: 05.01 - Describe the main extended entity relationship (EER) model constructs and how they are represented in ERDs and EERDs Copyright Cengage Learning. Powered by Cognero.Page 1 ____ 1. Entity supertypes and subtypes are organized in a specialization hierarchy. ____2.The relationships depicted within the specialization hierarchy are sometimes described in terms of is-a relationships. ____3.Within an specialization
hierarchy, a supertype can exist only within the context of a subtype. ____4.The entity supertype contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype. ____5.The property of subtype discriminator enables an entity supertype to inherit the attributes and relationships of the subtype. ____6.One important inheritance characteristic is that all entity subtypes inherit their primary key attribute from their supertype. ____7.At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a 1:1 relationship. ____8.Entity subtypes do not inherit the relationships in which the
supertype entity participates. ____9.In specialization hierarchies with multiple levels of supertype/subtypes, a lower-level supertype inherits all of the attributes and relationships from all of its upper-level subtype. ____10.An entity supertype can have disjoint or overlapping entity subtypes. ____11.Overlapping
subtypes are subtypes that contain a unique subset of the supertype entity set. ____12.Disjoint subtypes are subtypes that contain nonunique subsets of the supertype entity set. ____13.Implementing non-overlapping subtypes requires the use of one discriminator attribute for each subtype. ____14.The completeness
constraint can be partial or total. ____15.Specialization is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity supertype. ____16.Generalization is based on grouping unique characteristics and relationships of the subtypes. ____17.An entity cluster is a "virtual"
entity type used to represent multiple entities and relationships in the ERD. ____18.To model time-variant data, you must create a new entity in a M:N relationship with the original entity. ____19.A design trap occurs when a relationship is improperly or incompletely identified and, therefore, is represented in a way that is not consistent with the real world. ____20.Some designs use redundant relationships as a way to simplify the design. Do subtypes inherit relationships?Just as subtypes inherit relationships they also inherit any attributes of their supertype, and we also have that supertypes do not inherit the attributes of their subtypes.
What important inheritance characteristic that all entity subtypes inherit from their supertype?Cards
What kind of relationship is shared between an entity supertype and its subtypes?A supertype is a generic entity type that has a relationship with one or more subtypes. A subtype is a sub-grouping of the entities in an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other subgroups.
Can a subtype be a supertype?A supertype can have one or more subtypes, and a subtype can have one or more supertypes. A supertype can be a subtype of some other supertype, and a subtype can be a supertype of some other subtype.
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Entity subtypes do not inherit the relationships in which the supertype entity participates.
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