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Exam 8: Data Modeling Advanced Concepts

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Question 31

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The ____________________ constraint specifies whether each entity supertype occurrence must also be a member of at least one subtype.

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Question 32

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The ____________________ is the result of adding more semantic constructs to the original entity relationship (ER) model.

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extended entity relationship m...

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Question 33

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In what two cases are composite primary keys particularly useful?

Within a specialization hierarchy, every subtype can have ____ supertype(s) to which it is directly related.

Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed ____________________ in the M:N relationship.

Overlapping subtypes are subtypes that contain a unique subset of the supertype entity set.

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

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

In specialization hierarchies with multiple levels of supertype/subtypes, a lower-level supertype inherits all of the attributes and relationships from all of its upper-level subtypes.

The property of ____ enables an entity subtype to inherit the attributes and relationships of the supertype.

An entity supertype can have disjoint or overlapping entity subtypes.

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

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

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

The completeness constraint can be partial or total.

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

The "____" characteristic of a primary key states the following: The selected primary key must not be composed of any attribute(s) that might be considered a security risk or violation. For example, using a Social Security number as a PK in an EMPLOYEE table is not a good idea.

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.

When selecting a foreign key placement for a 1:1 relationship, place the PK of the entity on the mandatory side in the entity on the optional side as a FK, and make the FK mandatory when ____.

A ____ occurs when you have one entity in two 1:M relationships to other entities, thus producing an association among the other entities that is not expressed in the model.