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Exam 5: Advanced Data Modeling

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Question 31

True/False

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Specialization is the top-down process of identifying lower-level,more specific entity subtypes from a higher-level entity supertype.

A) True
B) False

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Question 32

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The depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities) .

A) subtype discriminator
B) inheritance
C) specialization hierarchy
D) entity supertype

E) A) and D)
F) A) and C)

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Question 33

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The purpose of a(n) is to simplify an entity-relationship diagram (ERD) and thus enhance its readability.

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

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

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

While using a surrogate key,one must ensure that the candidate key of the entity in question performs properly through the use of the " " and "not null" constraints.

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

The " " characteristic of a primary key states that the primary key should not have embedded semantic meaning.

Specialization is based on grouping characteristics and relationships of the subtypes.

Usually,a data modeler uses a natural identifier as the of the entity being modeled,assuming that the entity has a natural identifier.

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

is the bottom-up process of identifying a higher-level,more generic entity supertype from lower-level entity subtypes.

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

Entity supertypes and subtypes are organized in a specialization hierarchy.

To model time-variant data,one must create a new entity in an M:N relationship with the original entity.

Implementing nonoverlapping subtypes requires the use of one discriminator attribute for each subtype.

Which of the following is a specialization hierarchy disjoint constraint scenario in case of partial completeness?

A partial completeness constraint is represented by .

Subtypes that contain nonunique subsets of the supertype entity set are known as subtypes.