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Exam 5: Advanced Data Modeling

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Question 1

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The preferred placement for a foreign key when working with a 1:1 relationship is to ____.

A) use the same primary key for both entities
B) create a bridge entity
C) place a foreign key in one of the entities
D) place a foreign key in both entities

E) A) and B)
F) B) and D)

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Question 2

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Surrogate primary keys are especially helpful when there is no ____ key.

A) primary
B) natural
C) foreign
D) composite

E) B) and C)
F) A) and B)

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B

Question 3

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____ keys work with primary keys to properly implement relationships in the relational model.

Entity supertypes and subtypes are organized in a specialization hierarchy.

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

What do specialization hierarchies do?

The entity supertype contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype.

Some designs use redundant relationships as a way to simplify the design.

The main concern with redundant relationships is that they remain ____________________ across the model.

One important inheritance characteristic is that all entity subtypes inherit their primary key attribute from their supertype.

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

The most important characteristic of an entity is its ____ key,used to uniquely identify each entity instance.

If one exists,a data modeler uses a ____ as the primary key of the entity being modeled.

An entity supertype can have disjoint or overlapping entity subtypes.

Generalization is based on grouping unique characteristics and relationships of the subtypes.

What is an entity cluster?

A design trap occurs when a relationship is improperly or incompletely identified and is therefore represented in a way that is not consistent with the real world.

The completeness constraint can be partial or total.

Describe specialization and generalization.

____________________ completeness means that every supertype occurrence must be a member of at least one subtype.