--наше
WITH Zdfar202 AS
 (SELECT 1 AS ID, 2016 AS YEAR, 1 AS amnm, 1000 AS amna,
         to_date('10.07.2017', 'DD.MM.YYYY') AS date_mod
    FROM dual
  UNION
  SELECT 2 AS ID, 2015 AS YEAR, 0 AS amnm, 10000 AS amna,
         to_date('12.01.2017', 'DD.MM.YYYY') AS date_mod
    FROM dual
  UNION
  SELECT 3 AS ID, 2017 AS YEAR, 1 AS amnm, 5000 AS amna,
         to_date('19.02.2017', 'DD.MM.YYYY') AS date_mod
    FROM dual)
--ваше 
SELECT *
  FROM (SELECT t.amna,
               t.date_mod
          FROM Zdfar202 t
         WHERE t.YEAR IN (2016, 2017)
           AND t.amnm <> 0
         ORDER BY t.date_mod)
 WHERE ROWNUM = 1

SELECT *
  FROM (SELECT t$amna,
               t$date
          FROM baan.tzdfar202001
         WHERE t$YEAR IN (2016, 2017)
           AND t$amnm <> 0
         ORDER BY t$date /*здесь сортировка по дате*/)
 WHERE ROWNUM = 1/*выборка первой строки, т.е. с минимальной датой*/