>could you please let me know how to intercept it in between to give user messages.

It really depends on how you're submitting data to the server. If you're using SPT, on an error SQLEXEC() should return a -1. If you're using views, the TABLEUPDATE() should fail with a .F. In both cases, AERROR() will contain SQL Server's constraint violation error. It will be up to you to translate it into something that make sense to the users.

-Mike