[Zope] more on SQL tree structures.

I've got a db table that's essentially storing a tree of objects - ( obj_id int, parent_id int, name varchar ) I've got this working with the #tree display fine, with the help of the previous discussions on zope-list (thank god I index my mail spool) The next question is a bit trickier - Given an obj_id, I want to display (in zope) the list of parent_ids of it back to the root object - any ideas on the best way to do this loop? I can always just do it in an external method, but this seems like cheating to me. Anthony