Complete rules for n-ary relationship cardinality constraints

摘要

An extended approach is presented for modeling data relationships that involve multiple entities. This approach unifies the relationship cardinality constraints defined by a variety of existing approaches into a common framework and extends the types of constraints captured. A concise tabular notation for specifying such constraints is introduced. The result is a modeling technique that captures more completely the nature of data relationships. Rules are defined for identifying inconsistencies among cardinality constraints specified for a given data relationship. Specific subsets of these rules are shown to be complete for four of the most commonly used variations of cardinality constraints. These rules extend work done in axiomatization of functional and numerical dependencies for relational databases into the area of conceptual data models.