Modern Database Management Chapter 3

Enhanced entity-relationship (EER) model
a model that has resulted from extending the original E-R model with new modeling constructs
subtype
a subgrouping of the entities in an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other subgroupings
supertype
a generic entity type 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 (bottom-up)
specialization
the process of defining one or more subtypes of the supertype and forming supertype/subtype relationships
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 (double, bold line)
partial specialization rule
a rule that specifies that an entity instance of a supertype is allowed not to belong to any subtype (single, bold line)
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 or more subtypes
subtype discriminator
an attribute of a supertype whose values determine the target subtype or subtypes
supertype/subtype hierarchy
a hierarchical arrangement of supertypes and subtypes in which each subtype has only one supertype
entity cluster
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