oracle8.1.6
select c.category_id as linked_category_id, c.tree_id as linked_tree_id, l.link_id,
(case when l.from_category_id = :category_id then 'f' else 'r' end) as direction,
acs_permission.permission_p(c.tree_id,:user_id,'category_tree_write') as write_p
from category_links l, categories c
where (l.from_category_id = :category_id
and l.to_category_id = c.category_id)
or (l.from_category_id = c.category_id
and l.to_category_id = :category_id)