with
  cte(currency, type, date_oper) as
    (select
       round(dbms_random.value(800,840)), round(dbms_random.value(0,1)), sysdate - level/24
     from dual
     connect by level <= 100)
select
  t.currency,
  max(
      case
        when t.type = 0 then
          t.date_oper
      end
    ) last_sale,
  max(
      case
        when t.type = 1 then
          t.date_oper
      end
    ) last_buy
from cte t
group by t.currency