Integrating Triggers and Declarative Constraints in SQL Database Sytems

Abstract

This paper describes a model that integrates the execution of triggers with the evaluation of declarative constraints in SQL database systems. This model achieves full compatibility with the 1992 international standard for SQL (SQL92). It preserves the set semantics for declarative constraint evaluation while allowing the execution of powerful procedural triggers. It was implemented in DB2 for common servers and was recently accepted as the model for the emerging SQL standard (SQW).