Wendell;  thanks for your response.  To answer your question; users are using a form.  The errors mostly occur when a user navigates (accidentally tabbing from the last field onto the next row or clicking back on the main from) off of a from (Subfrom actually) without filling in all of the mandatory fields.  Can you tell me what properties of a form I would set?  Is it the approach that William suggests.

William;  thank you as well, for your response.  I have considered duplicating all of the database validation and if that's the way it has to be then that's what I'll do but to me that seems like a fail -effectively duplicating code.  I can't believe it's this difficult to trap and translate error messages coming from the server.