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Exam 3: The Enhanced E-R Model

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Question 41

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Regardless of the business situation, a member of the supertype is always a member of more than one subtype.

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Question 42

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Given the following entities, which of the choices below would be the most complicated? Automobile: VIN, EngineSize, NumberOfDoors, NumberOfPassengers, FuelType, Transmission SUV: VIN, EngineSize, NumberOfPassengers, NoWheelDrive, FuelType, Transmission Truck: VIN, EngineSize, NoWheelDrive, FuelType, Transmission, Payload

A) Define one vehicle entity type to hold all entities.
B) Define a separate entity type for each entity.
C) Define a supertype called vehicle and make each of the entities subtypes.
D) Keep only the Truck entity type.

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Question 43

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Subtypes at the lowest level of a hierarchy do not inherit attributes from their ancestors.

A completeness constraint may specify that each entity of the supertype must be a member of some subtype in the relationship.

There are three separate discriminators in the following diagram because of the overlap rule.

It is easier to share information across organizations if companies in the same industry use the same universal data model as the basis for their organizational databases.

A universal data model is a generic or template data model that can be reused as a starting point for a data modeling project.

When identifying the parts of the packaged data model that apply to your organization, one should first start with:

When the total specialization rule is set for a supertype/subtype relationship, one could roughly compare the supertype to an abstract class in object-oriented programming.

The following diagram is an example of a supertype/subtype hierarchy.

All of the following are advantages of packaged data models EXCEPT:

The process of defining one or more subtypes of a supertype and forming relationships is called:

A good method for identifying inconsistencies and finding hidden meaning in the customized purchased data model is:

An entity cluster can have a relationship with another entity cluster much the same way that an entity can have a relationship with another entity.

In a supertype/subtype hierarchy, subtypes that are lower in the hierarchy inherit attributes from not only their immediate supertype but from all ________ in the hierarchy.

A subtype is a generic entity that has a relationship with one or more entities at a lower level.

It is easy to miss the opportunity to visualize future requirements shown in the full data model when using a packaged data model.

An entity cluster can be formed by:

Creating a data model from a packaged data model requires much more skill than creating one from scratch.

The following figure is an example of: