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Exam 9: Object-Oriented Database Management

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Question 21

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Generalization/specialization is a relationship that can be handled directly by an OODBMS.

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Question 22

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In a generalization/specialization hierarchy, attributes can be inherited downwards from the general object class to the specialized object classes, but methods or operations cannot.

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Question 23

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In the object-oriented concept, abstract data types ____.

A video clip is an example of an abstract data type.

A potential exposure that can introduce errors in relational data is the ability of many application programs to manipulate shared data.

Generalization/specialization is a relationship that recognizes that some kinds of entities can really be subdivided into smaller, more specialized groups.

Aggregation relationships are handled naturally by relational DBMSs but generalization/specialization relationships are not.

Draw an object-oriented class diagram, including traditional unary, binary and ternary relationships, as well as generalization and aggregation relationships as needed, to represent the following Grand Travel Airlines environment. Include all of the attributes and operations listed in the description. Grand Travel Airlines operates as both a passenger and a cargo airline. It has different kinds of planes for each of the two functions. For planes of both types it keeps track of each plane's top speed, length, and range. In addition, it keeps track of the capacity (number of seats) of each passenger plane and the capacity (in tons or metric tons) of each cargo plane. Each passenger flight has a flight number, a date, departure time, and arrival time. A flight uses only one airplane while a particular plane is used on many flights. Grand Travel Airlines has two kinds of passenger planes: jet and propeller driven. For the propeller driven planes it must keep track of the maximum revolutions per minute (RPM) of the propellers. Each jet plane is composed of three parts: the fuselage, the wings, and the engines. Grand Travel records the fuselage height and width, the wingspan (length) of the wings, and the number of engines and their maximum thrust. An operation calculates the next maintenance date of each passenger plane, but the calculation is different for jet and propeller driven planes.

In a generalization/specialization hierarchy, attributes are inherited downwards from the general object class to the specialized object classes.

Generalization/specialization relationships are a form of aggregation relationships.

An OODBMS will only permit the attributes of an encapsulated object to be updated by its encapsulated methods or operations.

Generalization/specialization is a relationship in which a class is shown to be composed of other classes.

An object/relational DBMS is an OODBMS with relational features added to them.

The objects that describe similar entities are known collectively as a(n) ____.

Attributes in object classes in a generalization/specialization relationship ____.

All of the following are true about encapsulation, except ____.

Methods or operations cannot be modified when they are inherited downwards.

Relational database management systems directly support ____.

Generalization/specialization is denoted in a UML diagram by an arrow pointing upward towards the "general" object class.

The term for the relationship that recognizes that some kinds of entities can really be subdivided into smaller, more specific groups is ____.