Enhanced E-R Model Quiz

The property by which subtype entities possess the values of all attributes of a supertype is called:

• hierarchy reception.

• class management.

• attribute inheritance.

• generalization

Which of the following is a generic entity type that has a relationship with one or more subtypes?

• Megatype

• Supertype

• Subgroup

• Class

Given the following entities, which of the choices below would be the most complicated? Automobile: VIN, EngineSize, NumberOfDoors, NumberOfPassengers, FuelType, Transmission; SUV: VIN, EngineSize, NumberOfPassengers, NoWheelDrive, FuelType, Transmission; Truck: VIN, EngineSize, NoWheelDrive, FuelType, Transmission, Payload

• Define one vehicle entity type to hold all entities.

• Define a separate entity type for each entity.

• Define a supertype called vehicle and make each of the entities subtypes.

• Keep only the Truck entity type.

Subtypes should be used when:

• there are attributes that apply to some but not all instances of an entity type.

• supertypes relate to objects outside the business.

• the instances of a subtype do not participate in a relationship that is unique to that subtype.

• a recursive relationship is needed.

The process of defining one or more subtypes of a supertype and forming relationships is called:

• specialization.

• generalization.

• creating discord.

• selecting classes.

The process of defining a more general entity type from a set of more specialized entity types is called:

• generalization.

• specialization.

• normalization.

• extrapulation.

The ________ rule specifies that an entity instance of a supertype is allowed not to belong to any subtype.

• semi-specialization

• total specialization

• partial specialization

• disjointedness

The ________ rule specifies that each entity instance of the supertype must be a member of some subtype in the relationship.

• semi-specialization

• total specialization

• partial specialization

• total convergence

Which of the following is a completeness constraint?

• Total specialization

• Partial generalization

• Total recall

• Partial hybridization

A(n) ________ constraint is a type of constraint that addresses whether an instance of a supertype must also be an instance of at least one subtype.

• disjoint

• overlap

• completeness

• weak