Chapter+8+-+2

Chapter+8+-+2 - Data Modeling and Analysis Chapter 8...

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Data Modeling and Analysis Chapter 8 (Continued)
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Nonspecific Relationships Relationship where many instances of an Entity are associated with many instances of another Entity. Also called many-to- many relationship . Nonspecific relationships must be resolved, generally by introducing an Associative Entity .
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Resolving Nonspecific Relationships The verb or verb phrase of a Many-to-Many relationship sometimes suggests other Entities.
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Resolving Nonspecific Relationships (continued) Many-to-many relationships can be resolved with an Associative Entity.
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Resolving Nonspecific Relationships (continued) While the above relationship is a many-to-many, the many on the BANK ACCOUNT side is a known maximum of "2." This suggests that the relationship may actually represent multiple relationships. In this case two separate relationships. Many-to-Many Relationship
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Generalization Concept wherein the Attributes that are common to several types of an Entity are grouped into their own Entity. Supertype – Entity whose instances store Attributes that are common to one or more Entity subtypes. Subtype – Entity whose instances may inherit common Attributes from its Entity Supertype. And then add other Attributes unique to the Subtype.
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Generalization Hierarchy
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Process of Logical Data Modeling Strategic Data Modeling Many organizations select IS development projects based on strategic plans. Includes vision and architecture for Information
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Chapter+8+-+2 - Data Modeling and Analysis Chapter 8...

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