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Chapter 4: The Enhanced ER Model and Business Rules

2. Objectives. Definition of termsUse of supertype/subtype relationshipsUse of generalization and specialization techniquesSpecification of completeness and disjointness constraintsDevelop supertype/subtype hierarchies for realistic business situationsDevelop entity clustersExplain universal d

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Chapter 4: The Enhanced ER Model and Business Rules

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    1. © 2007 by Prentice Hall 1 Chapter 4: The Enhanced ER Model and Business Rules Modern Database Management 8th Edition Jeffrey A. Hoffer, Mary B. Prescott, Fred R. McFadden

    2. 2 Objectives Definition of terms Use of supertype/subtype relationships Use of generalization and specialization techniques Specification of completeness and disjointness constraints Develop supertype/subtype hierarchies for realistic business situations Develop entity clusters Explain universal data model Name categories of business rules Define operational constraints graphically and in English

    3. 3 Supertypes and Subtypes Subtype: A subgrouping of the entities in an entity type that has attributes distinct from those in other subgroupings Supertype: A generic entity type that has a relationship with one or more subtypes Attribute Inheritance: Subtype entities inherit values of all attributes of the supertype An instance of a subtype is also an instance of the supertype

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