A FUNDAMENTAL CLASSIFICATION OF ASSOCIATIONS IN RELATIONAL DATABASES
A fundamental classification is proposed for the associations that can occur beteween any two relations in a relational data base. Associations are first classified into primitive and composite associations. Essentially an association between relations A and B is primitive if both A and B contain attributes drawn on a common domain. A composite association can be decomposed into a chain of primitive associations. The most important primitive associations are the functional, multivalued and equivalence associations. The most important composite associations are the cascade, matrix, and cascade equivalence associations. Most primitive and composite associations have cyclic versions.