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Exam 8: Data Modeling Advanced Concepts

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Question 41

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____ data refer to data whose values change over time and for which you must keep a history of the data changes.

A) Time-sensitive
B) Time-variant
C) Historical
D) Change-based

E) A) and C)
F) All of the above

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Question 42

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Disjoint subtypes are also known as ____________________ subtypes.

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non-overla...

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Question 43

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Implementing non-overlapping subtypes requires the use of one discriminator attribute for each subtype.

Entity subtypes do not inherit the relationships in which the supertype entity participates.

At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a(n) ____ relationship.

A(n) ____ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.

Describe specialization and generalization.

Within a specialization hierarchy, a supertype can exist only within the context of a subtype.

The default comparison condition for the subtype discriminator attribute is the ____ comparison.

An entity cluster is considered "virtual" or "____________________" in the sense that it is not actually an entity in the final ERD.