Chapter 3 Flashcards
Which of the following is a generic entity type that has a relationship with one or more subtypes?
Supertype
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.
The property by which subtype entities possess the values of all attributes of a supertype is called:
attribute inheritance.
Subtypes should be used when:
there are attributes that apply to some but not all instances of an entity type.
The process of defining one or more subtypes of a supertype and forming relationships is called:
specialization.
The process of defining a more general entity type from a set of more specialized entity types is called:
generalization.
Which of the following is a completeness constraint?
Total specialization
The ________ rule specifies that an entity instance of a supertype is allowed not to belong to any subtype.
partial specialization
The ________ rule specifies that each entity instance of the supertype must be a member of some subtype in the relationship.
total specialization
A ________ constraint is a type of constraint that addresses whether an instance of a supertype must also be an instance of at least one subtype.
completeness
The ________ rule specifies that an entity can be a member of only one subtype at a time.
disjoint
A ________ addresses whether an instance of a supertype may simultaneously be a member of two or more subtypes.
disjointedness constraint
