Chap 3 Quiz

In packaged data models, strong entities always have ________ between them.

M:N relationships

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

Supertype

An entity cluster is:

a set of one or more entity types and associated relationships grouped into a single abstract entity type.

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

attribute inheritance.

The ________ rule states that an entity instance can simultaneously be a member of two (or more) subtypes.

overlap

The subtype discriminator is a composite attribute when there is a(n):

overlap rule

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

partial specialization

Packaged data models:

require customization.

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

specialization.

An attribute of the supertype that determines the target subtype(s) is called the:

subtype discriminator.

In a supertype/subtype hierarchy, subtypes that are lower in the hierarchy inherit attributes from not only their immediate supertype but from all ________ in the hierarchy.

supertypes

Subtypes should be used when:

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

In packaged data models, all subtype/supertype relationships follow the ________ and ________ rules.

total specialization; overlap

A generic or template data model that can be reused as a starting point for a data modeling project is called a(n):

universal data model.