Anonymous, I think your design has a major flaw: it is not provable to be correct. Your use of complex triggers which cannot be verified by reading them or running them seems to me to be dangerous to the integrity of your application. My experience has led me to perform the trigger functionality at the application level where it is simple and verifiable. Get rid of the triggers. If you generate different queries which test the conditions which your triggers are triggered on, then you can run the right insert or update query at the application level which handles the condition. The flow through the application is testable and not asynchronous and obtuse, as triggers are. And, of course, you can wrap the whole set of queries in a transaction for data integrity. My two cents...