Normalization
August 29, 2024Database-Management-System
August 29, 2024Database-Management-System
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Question 601
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What kind of mechanism is to be taken into account for converting a weak entity set into strong entity set in entity-relationship diagram ?
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Generalization
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Aggregation
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Specialization
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Adding suitable attributes
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Question 601 Explanation:
→ Entity types that do not have key attributes of their own are called weak entity types. In contrast,regular entity types that do have a key attribute are called strong entity types. Entities belonging to a weak entity type are identified by being related to specific entities from another entity type in combination with one of their attribute values. We call this other entity type the identifying or owner entity type, and we call the relationship type that relates a weak entity type to its owner the identifying relationship of the weak entity type.
→ A weak entity type always has a total participation constraint (existence dependency) with respect to its identifying relationship because a weak entity can not be identified without an owner entity.
→ A weak entity type always has a total participation constraint (existence dependency) with respect to its identifying relationship because a weak entity can not be identified without an owner entity.
Correct Answer: D
Question 601 Explanation:
→ Entity types that do not have key attributes of their own are called weak entity types. In contrast,regular entity types that do have a key attribute are called strong entity types. Entities belonging to a weak entity type are identified by being related to specific entities from another entity type in combination with one of their attribute values. We call this other entity type the identifying or owner entity type, and we call the relationship type that relates a weak entity type to its owner the identifying relationship of the weak entity type.
→ A weak entity type always has a total participation constraint (existence dependency) with respect to its identifying relationship because a weak entity can not be identified without an owner entity.
→ A weak entity type always has a total participation constraint (existence dependency) with respect to its identifying relationship because a weak entity can not be identified without an owner entity.