Exam 8: Data Modeling Advanced Concepts

Overlapping subtypes are subtypes that contain ____ subsets of the supertype entity set.

____ is a generic entity type that is related to one or more entity subtypes.

The "____" characteristic of a primary key states the following: The PK must uniquely identify each entity instance. A primary key must be able to guarantee unique values. It cannot contain nulls.

____ relationships occur when there are multiple relationship paths between related entities.

Non-overlapping subtypes are subtypes that contain a(n) ____ subset of the supertype entity set.

At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a 1:1 relationship.

One important inheritance characteristic is that all entity subtypes inherit their primary key attribute from their supertype.

Surrogate primary keys are especially helpful when there is no ____ key.

The main concern with redundant relationships is that they remain ____________________ across the model.

Entity supertypes and subtypes are organized in a specialization hierarchy.

Some designs use redundant relationships as a way to simplify the design.

A specialization hierarchy can have ____ level(s) of supertype/subtype relationships.

Usually, a data modeler uses a natural identifier as the ____________________ of the entity being modeled, assuming that the entity has a natural identifier.

The relationships depicted within the specialization hierarchy are sometimes described in terms of "is-a" relationships.

A ____ key is a real-world, generally accepted identifier used to uniquely identify real-world objects.

Composite keys are useful as identifiers of weak entities, where the weak entity has a strong ____________________ relationship with the parent entity.

An entity cluster is a "virtual" entity type used to represent multiple entities and relationships in the ERD.

____________________ completeness means that every supertype occurrence must be a member of at least one subtype.

If one exists, a data modeler uses a ____ as the primary key of the entity being modeled.

The "____" characteristic of a primary key states the following: The PK should not have embedded semantic meaning. An attribute with embedded semantic meaning is probably better used as a descriptive characteristic of the entity rather than as an identifier.