In an active database, an update may be constrained by integrity constraints, and may also trigger rules that, in turn, may a ect the database state. The general problem is to e ect the update while also managing the side-e ects" of constraint enforcement and rule execution. In this paper an update calculus is proposed by which updates, constraints and rules are speci ed and managed within the same formalism. Constraints and production rules are expressed in a constraint language based on

more »

... der logic. These logic expressions are used to semantically transform an original update into a sequence of updates that re ect the relevant constraints and production rules. The inference mechanism associated with processing a reformulated query ensures that: 1 the pre-and post-conditions of an update are satis ed, 2 update side-e ects are propagated, and 3 repairs are made to tuples exhibiting constraint violations. Thus, a user-speci ed update" is transformed, through semantic reformulation techniques, into a sequence of updates which together ensure semantic integrity of the original update as well as its propagated side-e ects.