oracle8.1.6
select message_id,
subject,
user_id,
posting_date,
state,
tree.tree_level(tree_sortkey) as tree_level
from forums_messages
where message_id in (select message_id
from forums_messages_pending
where forum_id = :forum_id)
or (tree_sortkey in (select substr(tree_sortkey, 1, 6)
from forums_messages_pending
where forum_id = :forum_id)
and forum_id = :forum_id)
order by tree_sortkey