Deductive databases are paraconsistent theory systems which change over time.
Moreover, computed answers in deductive databases typically make sense, almost no matter to which degree consistency or integrity is corrupted. Deductive databases evolve via sequences of state changes, effected by updates that can be seen as belief revision steps. Instead of rejecting update requests because of inconsistency or integrity violation, a certain amount of paraconsistency can be tolerated sometimes, in order to accommodate such requests. We recapitulate various forms of inconsistency and integrity violation in deductive databases. We investigate to which extent deductive databases can or do tolerate various degrees of paraconsistency.