I'm implementing a company rule in a informix 9.21 database.
With a trigger I execute a function that holds the rule,
when conditions aren't met I raise a custom error.
Dispite the error changes are made anyway!

create procedure check(num int)
if num > 100 then
RAISE EXCEPTION -746, 0, 'Not allowed';
end if
end procedure;

create trigger u_trig update of num on table
referencing old as pre new as post
for each row (
execute procedure check(post.num)

Using BEFORE I have to check all record in the table wich isn't exceptable.