Database Processing-Chapter 5

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Data Modeling with the Entity-Relationship Model

(T or F) 1) A data model is a plan for a database design.

TRUE
Diff: 1 Page Ref: 145

(T or F) 2) An entity is something that users want to track.

TRUE
Diff: 1 Page Ref: 145

(T or F) 3) Entities of a given type are grouped into entity classes.

TRUE
Diff: 1 Page Ref: 145

(T or F) 4) An entity class is described by the structure of the entities in that class.

TRUE
Diff: 2 Page Ref: 145

(T or F) 5) An entity instance of an entity class is the representation of a particular entity and is described by the values of the attributes of the entity.

TRUE
Diff: 3 Page Ref: 145-146

(T or F) 6) In E-R modeling, an attribute describes the characteristics of an entity.

TRUE
Diff: 1 Page Ref: 146

(T or F) 7) In E-R modeling, entities within an entity class may have different attributes.

FALSE
Diff: 1 Page Ref: 146

(T or F) 8) An identifier of an entity instance must consist of one and only one attribute.

FALSE
Diff: 1 Page Ref: 146-147

(T or F) 9) A "composite identifier" is defined as a composite attribute that is an identifier.

FALSE
Diff: 3 Page Ref: 146-147

(T or F) 10) An identifier serves the same role for a table that a key does for an entity.

FALSE
Diff: 2 Page Ref: 147

(T or F) 11) E-R modeling recognizes both relationship classes and relationship instances.

TRUE
Diff: 1 Page Ref: 147

(T or F) 12) In today's E-R models, attributes of relationships are still used.

FALSE
Diff: 2 Page Ref: 147

(T or F) 13) A single relationship class involves only one entity class.

FALSE
Diff: 3 Page Ref: 147

(T or F) 14) A binary relationship is a relationship based on numerical entity instance identifiers.

FALSE
Diff: 2 Page Ref: 148

15) The degree of a relationship is expressed as the relationship's maximum cardinality.
(T or F)

FALSE
Diff: 3 Page Ref: 148-150

(T or F) 16) When transforming a data model into a relational design, relationships of all degrees are treated as combinations of binary relationships.

TRUE
Diff: 2 Page Ref: 148

(T or F) 17) The principle difference between an entity and a table is that you can express a relationship between entities without using foreign keys.

TRUE
Diff: 2 Page Ref: 148

(T or F) 18) When designing a database, first identify the entities, then determine the attributes, and finally create the relationships.

FALSE
Diff: 3 Page Ref: 148

(T or F) 19) Relationships are classified by their cardinality.

TRUE
Diff: 1 Page Ref: 149

(T or F) 20) A relationship's maximum cardinality indicates the maximum number of entities that can participate in the relationship.

FALSE
Diff: 3 Page Ref: 149

(T or F) 21) In an E-R model, the three types of maximum cardinality are 1:1, 1:N and N:M.

TRUE
Diff: 1 Page Ref: 149-150 Fig 5-5

(T or F) 22) In a 1:N relationship, the term parent refers to the N side of the relationship.

FALSE
Diff: 2 Page Ref: 149

(T or F) 23) A relationship's minimum cardinality indicates whether or not an entity must participate in the relationship.

TRUE
Diff: 1 Page Ref: 149, 150

(T or F) 24) In an E-R model, the three types of minimum cardinality are mandatory, optional and indeterminate.

FALSE
Diff: 1 Page Ref: 150-15 Fig 5-6

(T or F) 25) An ID-dependent entity is an entity whose identifier includes the identifier of another entity.

TRUE
Diff: 2 Page Ref: 153 Fig 5-12

(T or F) 26) ID-dependent entities are associated by a nonidentifying relationship.

FALSE
Diff: 2 Page Ref: 154

(T or F) 27) A weak entity is an entity that cannot exist in the database without (and is logically dependent upon) another type of entity also existing in the database.

TRUE
Diff: 3 Page Ref: 155-156 Fig 5-12

(T or F) 28) ID-dependent entities are a common type of weak entity.

TRUE
Diff: 2 Page Ref: 154 Fig 5-12

(T or F) 29) All weak entities must have a minimum cardinality of 1 on the entity on which it depends.

TRUE
Diff: 3 Page Ref: 155-156 Fig 5-12

(T or F) 30) Subtype entities contain only attributes unique to the subtypes.

TRUE
Diff: 3 Page Ref: 156-157

(T or F) 31) An attribute that determines which subtype is appropriate is called a discriminator.

TRUE
Diff: 1 Page Ref: 157

(T or F) 32) An exclusive subtype pattern has one supertype entity that relates to one or more subtype entities.

FALSE
Diff: 2 Page Ref: 157

(T or F) 33) Entities with an IS-A relationship should have the same identifier.

TRUE
Diff: 2 Page Ref: 157

(T or F) 34) One example of a database design using an ID-dependent relationship is the association pattern.

TRUE
Diff: 2 Page Ref: 162

(T or F) 35) One example of a database design using a strong relationship is the multivalued attribute pattern.

FALSE
Diff: 2 Page Ref: 164

(T or F) 36) One example of a database design using an ID-dependent relationship is the archetype/instance pattern.

TRUE
Diff: 2 Page Ref: 166

(T or F) 37) Data modelers agree that weak, non-ID-dependent entities exist and are important.

FALSE
Diff: 2 Page Ref: 154-156

(T or F) 38) Relationships among instances of a single entity class are called redundant relationships.

FALSE
Diff: 2 Page Ref: 172

(T or F) 39) There are three types of recursive relationships: 1:1, 1:N and N:M.

TRUE
Diff: 2 Page Ref: 172-174

(T or F) 40) Recursive relationships only exist for one-to-one relationships.

FALSE
Diff: 1 Page Ref: 172-174

41) Which of the following is not a key element of an E-R model?
A) Identifiers
B) Entities
C) Objects
D) Attributes
E) Relationships

C
Diff: 2 Page Ref: 145-149

42) Entities of a given type are grouped into a(n) ________.
A) entity class
B) entity relationship
C) entity instance
D) entity attribute
E) None of the above.

A
Diff: 1 Page Ref: 145

43) The occurrence of a particular entity is called a(n) ________.
A) entity class
B) entity relationship
C) entity instance
D) entity attribute
E) None of the above.

C
Diff: 1 Page Ref: 145

44) The characteristics of a thing are described by its ________.
A) identifiers
B) entities
C) objects
D) attributes
E) relationships

D
Diff: 1 Page Ref: 146

45) Attributes may be ________.
A) composite
B) element
C) multivalued
D) A and C
E) B and C

D
Diff: 2 Page Ref: 146 and 150-151

46) An identifier may be ________.
A) composite
B) a single attribute
C) a relationship
D) A and B
E) A, B and C

D
Diff: 1 Page Ref: 146-147

47) A composite attribute is an attribute that ________.
A) is multivalued
B) describes a characteristic of the relationship
C) consists of a group of attributes
D) is calculated at run-time
E) is an identifier

C
Diff: 1 Page Ref: 147

48) For a relationship to be considered a binary relationship it must satisfy which of the following conditions?
A) It must involve exactly two entity classes.
B) It must have a maximum cardinality of 1:1.
C) It must have a maximum cardinality of 1:N.
D) A and B
E) A and C

A
Diff: 3 Page Ref: 147-149

49) Maximum cardinality refers to ________.
A) the most instances of one entity class that can be involved in a relationship instance with another entity class
B) the minimum number of entity classes involved in a relationship
C) whether or not an instance of one entity class is required to be related to an instance of another entity class
D) whether or not an entity is a weak entity
E) None of the above.

A
Diff: 2 Page Ref: 149

50) You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above, and are asked to draw the relationship between them. If a given customer can place only one order and a given order can be placed by at most one customer, which of the following should be indicated in the relationship symbol between the two entities?
A) 0:1
B) 1:1
C) 1:N
D) N:1
E) N:M

B
Diff: 2 Page Ref: 149-150

51) You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above, and are asked to draw the relationship between them. If a given customer can place many orders and a given order can be placed by at most one customer, which of the following should be indicated in the relationship symbol between the two entities?
A) 0:1
B) 1:1
C) 1:N
D) N:1
E) N:M

D
Diff: 3 Page Ref: 149-150

52) You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above, and are asked to draw the relationship between them. If a given customer can place many orders and a given order can be by one or more customers, which of the following should be indicated in the relationship symbol between the two entities?
A) 0:1
B) 1:1
C) 1:N
D) N:1
E) N:M

E
Diff: 2 Page Ref: 149-150

53) Minimum cardinality refers to ________.
A) the most instances of one entity class that can be involved in a relationship with one instance of another entity class
B) the minimum number of entity classes involved in a relationship
C) whether or not an instance of one entity class is required to be related to an instance of another entity class
D) whether or not an entity is a weak entity
E) None of the above.

C
Diff: 2 Page Ref: 150

54) In a minimum cardinality, minimums are generally stated as ________.
A) 0
B) 1
C) N
D) A or B
E) A, B or C

D
Diff: 2 Page Ref: 150-151

55) A hash mark across the relationship line near an entity indicates ________.
A) a maximum cardinality of "zero"
B) a maximum cardinality of "one"
C) a minimum cardinality of "optional"
D) a minimum cardinality of "required"
E) None of the above.

D
Diff: 2 Page Ref: 150-151

56) A circle across the relationship line near an entity indicates ________.
A) a maximum cardinality of "zero"
B) a maximum cardinality of "one"
C) a minimum cardinality of "optional"
D) a minimum cardinality of "required"
E) None of the above.

C
Diff: 2 Page Ref: 150-151

57) You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above. What does the symbol next to the ORDER entity indicate?
A) A maximum cardinality of "zero"
B) A maximum cardinality of "one"
C) A minimum cardinality of "optional"
D) A minimum cardinality of "required"
E) None of the above.

C
Diff: 2 Page Ref: 150-151

58) You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above. What does the symbol next to the CUSTOMER entity indicate?
A) A maximum cardinality of "zero"
B) A maximum cardinality of "one"
C) A minimum cardinality of "optional"
D) A minimum cardinality of "required"
E) None of the above.

D
Diff: 2 Page Ref: 150-151

59) An entity whose identifier includes the identifier of another entity is a(n) ________.
A) strong entity
B) weak entity
C) ID-dependent entity
D) A and C
E) B and C

E
Diff: 2 Page Ref: 153-154

60) An entity whose existence depends on the presence of another entity, but whose identifier does not include the identifier of the other entity is a(n) ________.
A) strong entity
B) weak entity
C) ID-dependent entity
D) A and C
E) B and C

B
Diff: 2 Page Ref: 154-156

61) An entity that holds specialized attributes that distinguish it from one or more other similar entities is a(n) ________.
A) supertype
B) subtype
C) discriminator
D) A and C
E) B and C

B
Diff: 1 Page Ref: 156-157

62) Which of the following is not true about subtype entities?
A) Subtypes may be exclusive.
B) The supertype and subtypes will have the same identifier.
C) Subtypes are used to avoid a situation in which some attributes are required to be null.
D) Subtypes have attributes that are required by the supertype.
E) Subtypes can produce a closer-fitting data model.

E
Diff: 3 Page Ref: 156-157

63) An attribute that determines which subtype should be used is a(n) ________.
A) supertype
B) subtype
C) discriminator
D) A and C
E) B and C

C
Diff: 1 Page Ref: 156-157

64) Discriminators can be ________.
A) exclusive only
B) inclusive only
C) decisive only
D) A or B
E) B or C

D
Diff: 1 Page Ref: 156-157

65) Supertype/subtype entities are said to have a(n) ________ relationship.
A) HAS-A
B) IS-A
C) recursive
D) redundant
E) multivalue

B
Diff: 2 Page Ref: 157

66) To represent an association pattern in an E-R model, ________.
A) create a new ID-dependent entity with a 1:1 relationship to one other entity
B) create a new weak, but not ID-dependent entity with a 1:1 relationship to one other entity
C) create a new strong entity with a 1:1 relationship to one other entity
D) create a new ID-dependent entity with a 1:N relationship to one of two parent entities
E) create a new weak, but not ID-dependent entity with a 1:N relationship to one of two parent entities

D
Diff: 3 Page Ref: 162-164

67) To represent a multivalued attribute in an E-R model, ________.
A) create a new ID-dependent entity with a 1:N relationship
B) create a new weak, but not ID-dependent entity with a 1:N relationship
C) create a new strong entity with a 1:1 relationship
D) create a new ID-dependent entity with a 1:1 relationship
E) create a new weak, but not ID-dependent entity with a 1:1 relationship

A
Diff: 3 Page Ref: 164-165

68) To represent an archetype/instance pattern in an E-R model, ________.
A) create a new ID-dependent entity with a 1:N relationship
B) create a new weak, but not ID-dependent entity with a 1:N relationship
C) create a new strong entity with a 1:1 relationship
D) create a new ID-dependent entity with a 1:1 relationship
E) create a new weak, but not ID-dependent entity with a 1:1 relationship

A
Diff: 3 Page Ref: 166-168

69) When an entity has a relationship to itself, we have a(n) ________.
A) supertype/subtype relationship
B) archetype/instance relationship
C) recursive relationship
D) A or C
E) B or C

C
Diff: 1 Page Ref: 172

70) Recursive relationships can have which of the following maximum cardinalities?
A) 1:1
B) 1:N
C) N:M
D) A or B
E) A, B or C

E
Diff: 1 Page Ref: 172-174

71) A(n) ________ is something that the users want to track in their environment.

entity
Diff: 1 Page Ref: 145

72) The method of constructing data models used in the text is the ________ model.

extended entity-relationship (E-R)
Diff: 1 Page Ref: 145

73) Entities of a given type are grouped into ________.

entity classes
Diff: 1 Page Ref: 145

74) A(n) ________ is the occurrence of a particular entity.

entity instance
Diff: 1 Page Ref: 145

75) A(n) ________ describes a characteristic of an entity.

attribute
Diff: 1 Page Ref: 146

76) A(n) ________ of an entity instance is one or more attributes that name or identify entity instances.

identifier
Diff: 1 Page Ref: 146-147

77) A(n) ________ is an identifier consisting of two or more attributes.

composite identifier
Diff: 2 Page Ref: 147

78) A(n) ________ serves the same role for an entity that a key does for a table.

identifier
Diff: 3 Page Ref: 147

79) Entities can be associated with one another in ________.

relationships
Diff: 1 Page Ref: 147

80) E-R modeling recognizes both relationship ________ and relationship ________.

classes; instances
Diff: 2 Page Ref: 147

81) A relationship class may involve ________ entity classes.

two or more
Diff: 3 Page Ref: 148

82) The ________ of a relationship is the number of entity classes in the relationship.

degree
Diff: 2 Page Ref: 148

83) A ________ is a relationship between two entities.

binary relationship
Diff: 2 Page Ref: 148

84) Relationships of degree two are referred to as ________ relationships.

binary
Diff: 2 Page Ref: 148

85) When transforming a data model into a relational design, relationships of all degrees are treated as combinations of ________.

binary relationships
Diff: 3 Page Ref: 148

86) The principle difference between an entity and a table is that you can express the relationship between entities without using ________.

foreign keys
Diff: 3 Page Ref: 148

87) Relationships are classified by their ________.

cardinality
Diff: 1 Page Ref: 149

88) A relationship's ________ indicates the maximum number of entity instances that can participate in the relationship.

maximum cardinality
Diff: 2 Page Ref: 149

89) The notation 1:N shows the relationship's ________.

maximum cardinality
Diff: 2 Page Ref: 149

90) In a 1:N relationship, ________ is on the one side of the relationship, and the ________ is on the many side of the relationship.

parent entity; child entity
Diff: 2 Page Ref: 149

91) A relationship's ________ indicates the number of entity instances that must participate in the relationship.

minimum cardinality
Diff: 2 Page Ref: 149, 150

92) An entity whose identifier includes the identifier of another entity is called a(n) ________ entity.

ID-dependent
Diff: 2 Page Ref: 153-154

93) An entity that represents something that can exist on its own is called a(n) ________ entity.

strong
Diff: 1 Page Ref: 153

94) E-R models use a(n) ________ to connect entities that are ID-dependent.

identifying relationship
Diff: 2 Page Ref: 154

95) Entities containing optional sets of attributes are often represented using ________.

subtypes
Diff: 2 Page Ref: 156-157

96) The ________ entity contains the attributes that are common to all subtypes.

supertype
Diff: 1 Page Ref: 156-157

97) An attribute that determines which subtype is appropriate is called a ________.

discriminator
Diff: 2 Page Ref: 157

98) Subtypes can be ________ or ________.

exclusive; inclusive
Diff: 2 Page Ref: 157

99) Relationships between supertypes and subtypes are called ________ relationships.

IS-A
Diff: 2 Page Ref: 157

100) Relationships among an entity instance of a single entity class are called ________ relationships.

recursive
Diff: 2 Page Ref: 172

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