Modern Database Management - Chapter 3 Vocabulary

Flashcards based on the Modern Database Management Thirteenth Edition Chapter 3: The Enhanced E-R Model

Enhanced E-R (EER) model

Extends original E-R model with new modeling constructs

Subtype

A subgrouping of the entities in an entity type that has attributes distinct from those in other subgroupings

Supertype

A generic entity type that has a relationship with one or more subtypes

Attribute Inheritance

Subtype entities inherit values of all attributes and relationships of the supertype; an instance of a subtype is also an instance of the supertype

Generalization

The process of defining a more general entity type from a set of more specialized entity types (Bottom-Up)

Specialization

The process of defining one or more subtypes of the supertype and forming supertype/subtype relationships (Top-Down)

Completeness Constraints

Whether an instance of a supertype must also be a member of at least one subtype

Total Specialization Rule

Yes (double line)

Partial Specialization Rule

No (single line)

Disjointness Constraints

Whether an instance of a supertype may simultaneously be a member of two (or more) subtypes

Disjoint Rule

An instance of the supertype can be only One of the subtypes

Overlap Rule

An instance of the supertype could be more than one of the subtypes

Subtype Discriminator

An attribute of the supertype whose values determine the target subtype(s)

Entity cluster

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

Universal data model

A generic or template data model that can be reused as a starting point for a data modeling project (also called a “pattern”)