>The current project I am working on will have table based validation/rules. However, we are still not sure if we will have the middle tier, or back end check the rules. If it is dones in the middle tier, we can verify either after the textbox loses focus OR on a save... however, if it is fired from .DBC or SQL rules, then the user could have put invalid data into a field and won't know about it until they hit save.

In my particular scenario we don't have a problem with making the user wait until they hit save, that's the way it's been done before but I see your point that the immediate feedback is usually more desireable. These comments were very helpful, and I would be interested on hearing more about what you decide to do with your similar situation. Thanks!