First, INSERT statements are 1 to 1 with table rows... (unless you use
a insert/select).
Second, if you want to probe that.. it is better to create an UNIQUE
index.. isn't it?
Ok, if that's not enough for you... you can create a trigger that
perform a SELECT COUNT(*) with the criteria and if it's > 0, you rise
an exception (sorry, I don't have access to a databae now to check the
code).
Juan C. Olivares
www.juancri.com