DBMS Multiple choice Questions and Answers-Data Models

91.	Which of the following is true concerning the following statement: class Manager extends Employee
a.	Manager is a concrete class and a superclass.
b.	Manager is a concrete class and a subclass.
c.	Manager is an abstract class and a superclass.
d.	Manager is an abstract class and a subclass.

Answer: (b).Manager is a concrete class and a subclass.

92.	The reserved word enum is used for which of the following?
a.	To define a range for an attribute.
b.	To define a range for a class.
c.	To define a range for a relationship.
d.	All of the above.

Answer: (a).To define a range for an attribute.

93.	ODL supports which of the following types of association relationships?
a.	Unary
b.	Unary and Binary
c.	Unary and Binary and Ternary
d.	Unary and Binary and Ternary and higher

Answer: (b).Unary and Binary

94.	An atomic literal is which of the following?
a.	Strings
b.	Boolean
c.	Long
d.	All of the above.

Answer: (d).All of the above.

95.	The keyword "inverse" is used in which of the following?
a.	Class
b.	Attribute
c.	Relationship
d.	All of the above.

Answer: (c).Relationship

96.	An extent is which of the following?
a.	A keyword that indicates that the subclass inherits from a superclass
b.	A keyword that indicates that the superclass inherits from a subclass
c.	The set of all instances of a class within a database
d.	Only one instance of a class within a database

Answer: (c).The set of all instances of a class within a database

97.	Which of the following is true concerning an ODBMS?
a.	They have the ability to store complex data types on the Web.
b.	They are overtaking RDBMS for all applications.
c.	They are most useful for traditional, two-dimensional database table applications.
d.	Both a and c

Answer: (d).Both a and c

98.	Which of the following is not a logical data-base structure?
a.	tree
b.	relational
c.	network
d.	chain

Answer: (d).chain

99.	The relational model uses some unfamiliar terminology. A tuple is equivalent to a:
a.	record
b.	field
c.	file
d.	data base

Answer: (a).record

100.	A top-to-bottom relationship among the items in a database is established by a
a.	Hierarchical schema
b.	Network schema
c.	Relational schema
d.	All of the above

Answer: (a).Hierarchical schema