With t As
 (Select '706030' saccount,
         350 nsumm,
         to_date('01/08/2018', 'DD/MM/YYYY') ddate
    From dual
  Union All
  Select '706040' saccount,
         500 nsumm,
         to_date('01/08/2018', 'DD/MM/YYYY') ddate
    From dual
  Union All
  Select '706040' saccount,
         500 nsumm,
         to_date('01/08/2018', 'DD/MM/YYYY') ddate
    From dual
  Union All
  Select '706030' saccount,
         250 nsumm,
         to_date('01/01/2017', 'DD/MM/YYYY') ddate
    From dual
  Union All
  Select '706030' saccount,
         450 nsumm,
         to_date('01/01/2017', 'DD/MM/YYYY') ddate
    From dual
  Union All
  Select '706040' saccount,
         300 nsumm,
         to_date('01/01/2017', 'DD/MM/YYYY') ddate
    From dual)
Select *
  From t