error handling - rolling back changes

hello. i'm trying to incorporate some error handling into my web app,
but i'm not sure how to go about it in this case.

say for example, i already ran 10 INSERTS, then on my 11th INSERT,
something fails (perhaps trying to perform an INSERT into a table that
doesn't exist). logically, i should stop execution of the page and
display some sort of error message. but, since i've already run 10
successful INSERT queries before the error occurred, what do i do
now?

thanks