I was poking around in the database to see what it would take to run a query of the contents of a folder. You have to join OH (object table) to OFS (folder relationship table) like so;
select oh_name
from ofs, oh
where ofs_oh_idnr_f = 1006459
and oh_idnr = ofs_oh_idnr_o;
The ofs table has one row for each folder. So if you are looking for objects in folder L1/L2/L3, these are represented by three different rows in the oh table that have relationships to one another. In my case I wanted to know the objects that were stored in L3, so I found its oh_idnr and used that in my query.