--环比去年，row_number() over()取最新版本

--环比去年 and substr(last_sum.dbilldate,1,4) = to_char(add_months(to_date(substr(tmp.dbilldate,1,7),'yyyy-mm'),-12),'yyyy')
row_number() over()取最新版本
select iversion
from so_saleorder

    select tmp.pk_order
      from (select pk_order,
                   row_number() over(partition by vbillcode order by nversion desc) as rn
              from po_order
             where dr = 0
               and vbillcode = '       vbillcode
					         ') tmp
     where tmp.rn = 1

select * from ent_contract