[Zope] dtml-tree and Z SQL methods

Does anyone know how to display hierarchical content from SQL? I was hoping to find the answer in the "Secrets of working with the tree tag"-HOWTO but appearently it's not yet in there. What I have in (My)SQL is a table with: cont_id - Unique ID (primary key) of a container upper_id - ID of the upper container or NULL (the container containing this container;) description - text to be displayed describing the container Ragnar Beer