Using active rules or triggers to verify integrity constraints is a serious and complex problem because these mechanisms have behaviour that could be difficult to predict in a complex database. The situation is even worse as there are few tools available for developing and verifying them. We believe that automatic support for trigger development and verification would help database developers to adopt triggers in the database design process. Therefore, in this work we suggest a visualization add-in tool that represents and verifies triggers execution by using UML’s sequence diagrams. This tool is added in RATIONAL ROSE and it simulates the execution sequence of a set of triggers when a DML operation is produced. This tool uses the SQL standard to express the triggers semantics and execution.