IS 410 - Ch 3

92) Explain the terms subtype and supertype. Discuss the differences between them.

A subtype is an entity which represents data meaningful to the organization. For example, an undergraduate student and a graduate student might be a subtype. A supertype is a generalization of various subtypes and contains attributes which are common to both. Supertypes and subtypes may have relationships with other entities. Also, a subtype inherits the attributes of its supertype

32) Which statement is true about the following diagram?

A) A person can only be a faculty, student, or staff.

3) 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.

22) The subtype discriminator in the figure below is:

A) Part_Type.

13) Which of the following is a completeness constraint?

A) Total specialization

15) In the figure below, a student:

A) must be a graduate student, an undergraduate, a special student or some other type of student.

25) In a supertype/subtype hierarchy, each subtype has:

A) only one supertype.

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

A) specialization.

4) Subtypes should be used when:

A) there are attributes that apply to some but not all instances of an entity type.

26) Which of the following statements is true about the figure shown below?

B) A rental unit can be an apartment, house or just a rental unit; it may not be more than one at the same time.

91) Explain why the E-R model needed to be expanded into the enhanced E-R model.

Business relationships are more complex, and organizations must have ways to represent data to represent the complexity. Organizations must be prepared to segment their markets as well as customize their products. The enhanced E-R model has evolved to represent these changes and also is similar to the object-oriented data mode

27) Which of the following statements is true about the figure shown below?

C) A rental unit must be either an apartment or a house, and could be both.

In the figure below, which of the following apply to both OUTPATIENTs and RESIDENT_PATIENTs?

C) Patient_Name

29) Which of the following statements is true about the figure shown below?

D) A rental unit can be an apartment, a house or just a rental unit. It could be both an apartment and a house at the same time.

The property by which subtype entities possess the values of all attributes of a supertype is called:

D) attribute inheritance.

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

False

50) A member of a subtype does NOT necessarily have to be a member of the supertype.

False

56) Generalization is a top-down process.

False

77) Packaged data models use an entity type to store union data.

False

79) Packaged data models cause projects to take more time to build.

False

81) Data models of an existing database are harder for data modelers to read.

False

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

False

87) You will never need to map data in current databases to data in a packaged data model.

False

Adapting a packaged data model from your DBMS vendor makes it difficult for the application to work with other applications from the same vendor.

False

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

False

The disjoint rule specifies that if an entity instance of the supertype is a member of one subtype, it MUST simultaneously be a member of another subtype.

False

The total specialization rule states that an entity instance of a supertype is allowed not to belong to any subtype.

False

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.

False

6) In the figure below, which of the following is a subtype of patient?

Outpatient

Which of the following is a generic entity type that has a relationship with one or more subtypes?

Supertype

49) An entity instance of a subtype represents the same entity instance of the supertype.

True

54) Specialization is the reverse of generalization.

True

76) Packaged data models are meant to be customized.

True

80) Packaged data models can be developed using proven components.

True

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

True

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

True

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.

True

An entity cluster should focus on some area of interest to some community of users, developers, or managers

True

Because a purchased data model is extensive, you begin by identifying the parts of the data model that apply to your data modeling situation.

True

Entity clustering is a methodology for grouping one or more entity types and associated relationships into a single abstract entity type.

True

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.

True

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

True

Mapping existing data to new data in a packaged data model is useful for developing migration plans.

True

One of the major challenges in data modeling is to recognize and clearly represent entities that are almost the same.

True

Packaged data models are as flexible as possible, because all supertype/subtype relationships allow the total specialization and overlap rules.

True

Supertype/subtype relationships should not be used when the instances of a subtype participate in no relationships which are unique to that subtype.

True

The most important challenge of customizing a purchased data model is determining the business rules that will be established through the data model.

True

8) In the figure below, to which of the following entities are the entities "CAR" and "TRUCK" generalized?

Vehicle

18) In the figure below, the patient must be either an outpatient or a resident patient. This is an example of the ________ rule.

disjoint

9) The process of defining a more general entity type from a set of more specialized entity types is called:

genralization

19) An attribute of the supertype that determines the target subtype(s) is called the:

subjoint discriminator

21) The following diagram shows:

subtype discriminator

31) The following figure shows a:

supertype/subtype hierarchy.

24) The following figure shows an example of:

the overlap rulw

10) The following figure is an example of:

total specialization