COMPLETE RULES FOR N-ARY RELATIONSHIP CARDINALITY CONSTRAINTS

An extended approach is presented for modeling data relationships that involve multiple entities. This approach unifies the relationship car dinality constraints defined by a variety of existing approaches into a common framework and extends the types of constraints captured. A co ncise tabular notation for specifying such constraints is introduced. The result is a modeling technique that captures more completely the n ature of data relationships. Rules are defined for identifying inconsi stencies among cardinality constraints specified for a given data rela tionship. 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 nume rical dependencies for relational databases into the area of conceptua l data models. (C) 1998 Elsevier Science B.V. All rights reserved.