Update Contraints for Relational Databases

We treat relational database constraints as formulas in a bounded first-order logic. A database is said to be in a consistent state if all its constraints are met in that state. The basic problem of integrity maintenance is to ensure that transactions never leave a database in an inconsistent state. We present a simple language for transactions and present an effective algorithm for the maintenance of database integrity based on the generation of update constraints. This paper was motivated by the ongoing development and implementation of PRL5.0, the language used to specify integrity constraints for the 5ESS database.