Patent ID: RE40063

Claim:
In a computer system, a data processing system for maintaining cardinality in a relational database, said data processing system comprising: memory means containing (i) relation definition table means comprised of at least one relation type record wherein each relation type record defines a relation type and includes cardinality data defining cardinality of said relation type and (ii) relation instance table means comprised of at least one relation instance record, wherein said relation definition table means and said relation instance table means are a part of said relational database; means, operatively coupled to said relation definition table means and said relation instance table means, for storing a plurality of relation instance records in said relation instance table means, wherein each relation instance record defines a relation of one of said relation types and further wherein said relation is between two entities; and means, operatively coupled to said relation instance record storing means, for detecting a cardinality violation for a first relation type, said means for detecting comprising means for determining whether said relation instance table means contains a first relation instance record, that defines a first relation of said first relation type between a first entity and a second entity; and means for determining whether said relation instance table means contains a second relation instance record that defines a second relation of said first relation type between said first entity and a third entity.