Extended Entity-Relationship Model Quiz

What does the Extended Entity-Relationship Model (EERM) address?

• Simple data structures

• The need for less complex data models

• The growing complexity of data structures and software requirements

• The elimination of the entity-relationship model

What is the primary benefit of using entity supertypes and subtypes?

• To increase the number of attributes

• To eliminate redundant data

• To avoid unnecessary nulls and support unique relationships

• To combine all attributes into one table

In which scenario would you use specialization in data modeling?

• When combining common attributes into a superclass

• When grouping unique characteristics of subclasses

• When eliminating unique relationships

• When creating a bottom-up model

What is the purpose of a subclass discriminator?

• • a) To combine two subtypes

• • To determine which superclass an entity belongs to

• • To define the membership of an entity in a subclass

• To eliminate overlapping subclasses

Which constraint ensures that an entity can only belong to one subclass?

• Overlapping

• Nullifying

• Disjoint

• Comprehensive

What symbol is used to denote an overlapping subclass?

• d

• o

• s

• u

What approach is used when defining a set of subclasses from an entity type?

• Generalization

• Specialization

• Aggregation

• Classification

What attribute in the superclass determines to which subclass an entity belongs?

• Subclass Discriminator

• • Primary Key

• • Entity Identifier

• • Foreign Key

Which criterion must be met to determine when to use subtype and supertype?

• Entities must have the same attributes

• There must be different identifiable types of entities

• Subtypes must not overlap

• All instances must belong to the same class

Which of the following represents an example of specialization?

• Creating a VEHICLE entity from CAR and TRUCK

• combining a PILOT and EMPLOYEE entity

• showing an EMPLOYEE and PILOT entity

• Combining SECRETARY and TECHNICIAN into one entity