ER Model and Business Rules Questions and Answers

Q: Packaged data models are meant to be exactly right straight out of the box.

Correct answer: FalseA packaged model is a starting point built from experience in an industry, and it saves a great deal of the initial work. It still has to be tailored, because no two organisations define their entities identically. Taking one as correct out of the box means adopting someone else’s definitions of the business.

Q: An action assertion is a statement that expresses some aspect of the static structure of the organization.

Correct answer: FalseA statement about static structure is a term or a fact. An action assertion constrains behaviour - what may happen, under what conditions, and by whom. The statement has attached the definition of the structural kind of rule to the name of the behavioural one.

Q: A supertype is an entity type that shares common attributes or relationships distinct from other subgroupings.

Correct answer: FalseThat is the definition of a subtype - a subgrouping sharing attributes or relationships distinct from the other subgroupings. A supertype is the general entity type whose attributes and relationships are shared by all of them. The statement has given one definition under the other name.

Q: Which one of the following symbols is not used in an ERD?

Correct answer: CircleThe three shapes of the basic notation are the rectangle for an entity, the oval for an attribute and the diamond for a relationship. Optionality and cardinality are shown by marks on the relationship lines - crow’s feet and strokes - rather than by a shape, so no circle appears.

Q: An action assertion must include which of the following?

Correct answer: All of the above.An action assertion constrains behaviour, and to do so it must name what is constrained, what the constraint is, and what it is constrained against - the anchor object, the action, and the corresponding object. Omit any one and the rule cannot be enforced because something essential is left unstated.

Q: A supertype can only have only one subtype.

Correct answer: FalseA supertype ordinarily has several subtypes, since the point of the construct is to distinguish kinds. A single subtype is possible but unusual and generally means the modeller has found an exception rather than a genuine classification.

Q: An entity instance of a subtype represents the same entity instance of a supertype.

Correct answer: TrueThe supertype and the subtype are two views of one thing, not two things. An instance of the subtype is the corresponding supertype instance, which is what makes attribute inheritance meaningful and why the relationship carries no cardinality.

31.

Packaged data models are meant to be exactly right straight out of the box.

A.True
B.False

Answer: B

Correct answer: False

A packaged model is a starting point built from experience in an industry, and it saves a great deal of the initial work. It still has to be tailored, because no two organisations define their entities identically. Taking one as correct out of the box means adopting someone else’s definitions of the business.

Discuss in Forum

32.

An action assertion is a statement that expresses some aspect of the static structure of the organization.

A.True
B.False

Answer: B

Correct answer: False

A statement about static structure is a term or a fact. An action assertion constrains behaviour - what may happen, under what conditions, and by whom. The statement has attached the definition of the structural kind of rule to the name of the behavioural one.

Discuss in Forum

33.

A supertype is an entity type that shares common attributes or relationships distinct from other subgroupings.

A.True
B.False

Answer: B

Correct answer: False

That is the definition of a subtype - a subgrouping sharing attributes or relationships distinct from the other subgroupings. A supertype is the general entity type whose attributes and relationships are shared by all of them. The statement has given one definition under the other name.

Discuss in Forum

34.

Which one of the following symbols is not used in an ERD?

A.Rectangle
B.Oval
C.Diamond
D.Circle

Answer: D

Correct answer: Circle

The three shapes of the basic notation are the rectangle for an entity, the oval for an attribute and the diamond for a relationship. Optionality and cardinality are shown by marks on the relationship lines - crow’s feet and strokes - rather than by a shape, so no circle appears.

Discuss in Forum

35.

An action assertion must include which of the following?

A.Anchor object
B.Action
C.Corresponding object
D.All of the above.

Answer: D

Correct answer: All of the above.

An action assertion constrains behaviour, and to do so it must name what is constrained, what the constraint is, and what it is constrained against - the anchor object, the action, and the corresponding object. Omit any one and the rule cannot be enforced because something essential is left unstated.

Discuss in Forum

36.

A supertype can only have only one subtype.

A.True
B.False

Answer: B

Correct answer: False

A supertype ordinarily has several subtypes, since the point of the construct is to distinguish kinds. A single subtype is possible but unusual and generally means the modeller has found an exception rather than a genuine classification.

Discuss in Forum

37.

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

A.True
B.False

Answer: A

Correct answer: True

The supertype and the subtype are two views of one thing, not two things. An instance of the subtype is the corresponding supertype instance, which is what makes attribute inheritance meaningful and why the relationship carries no cardinality.

Discuss in Forum

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ER Model and Business Rules Questions and Answers

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