--
-- content_folder__is_sub_folder/2
--
create or replace function content_folder__is_sub_folder(
  is_sub_folder__folder_id integer,
  is_sub_folder__target_folder_id integer
) returns bool as $$


  WITH RECURSIVE parents AS (
       select item_id, parent_id from cr_items where item_id = is_sub_folder__target_folder_id
    UNION ALL
       select cr_items.item_id, cr_items.parent_id from cr_items, parents
       where cr_items.item_id = parents.parent_id
  )
  SELECT EXISTS (
    SELECT 1 FROM parents WHERE parent_id = is_sub_folder__folder_id
  );
$$ language plpgsql;