Chapter 3 Vocab Flashcards
Enhanced ER Model
a model that has resulted from extending the original ER model with new modeling constructs
Subtype
a subgrouping of entities in an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other sungroupings
Supertye
a generic entity type that has a relationship that has a relationship with one or more subtypes
Attribute Inheritance
a property by which subtype entities inherit values of all attributes and instances of all relationships of their supertype
Generalization
the process of defining a more general entity type from a set of more specialized entity types
Completeness Constraint
a type of constraint that addresses whether an instance of a supertype must also be a member of at least one subtype
Total Specialization Rule
a rule that specifies that each entity instance of a supertype must be a member of some subtype in the relationship
Partial Specialization Rule
a rule that specifies that an entity instance of a supertype is allowed not to belong to any subtype
Disjointness Constraint
a constraint that addresses whether an instance of a supertype may simultaneously be a member of two or more subtypes
Disjoint Rule
a rule that specifies that an instance of a supertype may NOT simultaneously be a member of two or more subtypes
Overlap Rule
a rule that specifies that an instance of a supertype may simultaneously be a member of two subtypes
Subtype Discriminator
an attribute of a supertype whose values determine the target subtype(s)
Supertype/subtype Hierarchy
an hierachical arrangement of supertypes and subtypes in which each subtype has only one supertype
Entity Clustering
a 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
