quote:

---

Generally, most things can be trapped but the more error trapping is done at the SQL end the bigger the performance hit.

If there are going to be multiple apps hitting a database then I put more error trapping in the database and middle tier. If there are very few apps then I expect the app to take the burden of the error trapping.

---

 
IF NOT EXISTS (SELECT 1 FROM MyTable WHERE MyField = @Value)
    BEGIN
        INSERT MyTable(My Field) VALUES (@Value)
        RETURN 1
    END
ELSE
    BEGIN
        RAISERROR('My bespoke PK Error',10,1)
        RETURN 0
END

  INSERT MyTable(My Field) VALUES Where MyField <> @Value

IF @@ROWCOUNT = 0 
 RAISERROR('My bespoke PK Error',10,1)