Here is a version that finds objects that have no statistics, and I added a filter to remove objects from the list that typically don't have statistics. Finding unused variables, promptsets, and things like that will require a very different search. (I did this on SQLServer)
SELECT OH_Client AS "Client", OH_Name AS "Name", oh_OType as "Type",
OH_LastDate AS "Date"
FROM OH
WHERE OH_Client = 100
and oh_deleteflag = 0
and not OH_OType in ('FOLD', 'VARA', 'USER', 'SYNC', 'USRG', 'LOGIN', 'PRPT', 'JOBI', 'FILTER', 'CONN')
and not exists (select 1 from ah where ah_oh_idnr = oh_idnr)