 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
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What is an overlapping subtype?Overlapping subtypes are subtypes that contain nonunique subsets of the supertype entity set; that is, each entity instance of the supertype may appear in more than one subtype. For example, in a university environment, a person may be an employee or a student or both.
How many Supertypes can a subtype be directly related to?However, a subtype is (directly) a subtype of only one supertype. Thus, the use of supertypes and subtypes in ERDs resembles the use of ``single inheritance'' between classes, in object-oriented programming.
What is an entity supertype and subtype and why is it used?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.
Is the attribute in the supertype entity that determines to which subtype the supertype occurrence is related?Cards
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Overlapping subtypes are subtypes that contain a unique subset of the supertype entity set.
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