Here is a database query I use with my auditors. I shows who is in which security groups, when they last signed on, and weather or not the user has been set inactive. (We don't delete users because doing so logically orphans their history.)
select oh2.oh_name as 'GROUP'
, oh2.oh_client as 'CLIENT'
, oh1.oh_name as 'USER'
, case USR_Active
when 0 then 'INACTIVE'
else ' '
end as STATE
, USR_LastSession as LAST_USED
from oh as oh1
,oh as oh2
,usr
,usrg
,USG
where oh1.oh_idnr=USR_OH_Idnr
and USRG_USR_Idnr=USR_OH_Idnr
and usrg_usg_idnr = usg_oh_idnr
and USG_OH_Idnr=oh2.oh_idnr
order by 1, 2, 3