Остатки на дату : Oracle

select sum(decode(t.doctype,
                  'WI',
                  t.quantity,
                  'WO',
                  -t.quantity,
                  'CR',
                  t.quantity,
                  'CS',
                  -t.quantity,
                  'PD',
                  t.quantity,
                  'PE',
                  -t.quantity)) quant,
       t.article article,
       nvl(d.locationto, d.locationfrom) loc,
       0 as price,
       to_date('01.01.2007', 'DD.MM.YYYY') date_price
  from smspec t, smdocuments d
 where t.doctype = d.doctype
   and t.docid = d.id
   and d.createdat < &DateEnd
   and d.docstate > 2
   and d.doctype in ('WI', 'WO', 'CS', 'CR', 'PE', 'PD')
   and nvl(d.locationto, d.locationfrom) = &LocId
--     and t.article='80419'
 group by t.article, nvl(d.locationto, d.locationfrom)