create exception invalid_date 'Blah';
commit;

create trigger....

declare vali_date date;
as
begin
select BDate from B where B.cd = new.cd
into :vali_date;
if (vali_date <= new.ADate) then
exception invalid_date 'Date must be later than '||cast (:vali_date as
char(11));
end

/heLen

Thank you Helen

This was exactly what i wanted

Regards
Alfred