On rules and integrity constraints in database systems

T.W. Ling, P.K. Teo
1992 Information and Software Technology  
Recently, several researchers have proposed incorporating rules into database systems. These rules typically embody several diverse concepts, eg. deductive rules, production rules, and authorisation rules. However, most systems treat these diverse concepts homogeneously. Their roles are often misunderstood because of this lack of distinction. This paper clarifies the concepts of deductive rules, production rules, authorisation rules and integrity constraints and point out the essential
more » ... es among them. A framework for comparison is established. Several problems with current implementations of the rule mechanisms are highlighted. We also highlight the advantages and disadvantages of each of these concepts and the domains for which they are suitable. Introduction Recently, several researchers have proposed incorporating rules in object-oriented database systems (OODBMSs) [6, 25, 9] . These rules capture additional semantics (knowledge) for the database. The rule mechanisms employed in these systems often embody several diverse concepts eg. deductive rules, production rules and authorisation rules. The different forms of rules have different functions. However, most systems treat these diverse concepts homogeneously. Their roles are often misunderstood because of this lack of distinction. Deductive rules[21] provide a mechanism to derive data which are not explicitly stored in the database. This is the concept of virtual or derived data. Deductive rules are more powerful and expressive than relational views. However, support for deductive rules can be problematic with negative information and recursion. formula [17] . In [17] , it was shown that an integrity constraint which involves universal quantifiers, existential quantifiers, negative conditions and/or disjunctive conditions can be expressed by an ICformula easily. IC-formula is more powerful and expressive than some of the other methods of representing integrity constraints, eg. tuple calculus, closed first order formula, clause [2, 5] etc. We refer the reader to [17] for a formal definition of IC-formula.
doi:10.1016/0950-5849(92)90026-l fatcat:tpqdq552pzfzbeyt3rngjo3lq4