oracle8.1.6
insert into advs (adv_key, target_url, local_image_p, track_clickthru_p, adv_filename)
select :adv_key, :target_url, :local_image_p, :track_clickthru_p, :adv_filename
from dual
where not exists (select 1
from advs
where adv_key= :adv_key)