-- 답에만 맞췄습니다. WITH T ( V1 , V2 ) AS ( SELECT 'A', NULL FROM DUAL UNION ALL SELECT 'A', '2018-01-02' FROM DUAL UNION ALL SELECT 'B', '2018-01-01' FROM DUAL UNION ALL SELECT 'B', '2018-02-02' FROM DUAL UNION ALL SELECT 'B', NULL FROM DUAL UNION ALL SELECT 'C', NULL FROM DUAL ) SELECT V1 , MAX(V2) AS V2 FROM T GROUP BY V1