ROW_NUMBER  추가로 쓰고 번호줘서 1번만 출력하게 하면 될것 같습니다.

다만 공백으로 나오게 할려면 숫자부분을 문자로 바꾸셔야 될것 같습니다.

;with MA170MP AS

(

       SELECT 'PO-131210-RM-01' AS  maqpono, '1' AS maqposeq, '9' AS maqhqty, '1' AS maqbqty

       UNION ALL

       SELECT 'PO-131210-RM-01' AS  maqpono, '2' AS maqposeq, '10' AS maqhqty, '2' AS maqbqty

       UNION ALL

       SELECT 'PO-131210-RM-01' AS  maqpono, '3' AS maqposeq, '18' AS maqhqty, '0' AS maqbqty

)

, MA180MP AS

(

       SELECT 'PO-131210-RM-01' AS MARPONO, '1' AS MARPOSEQ, 'AAA' AS marhtno, 9 AS marhqty, 1 AS marbqty

       UNION ALL

       SELECT 'PO-131210-RM-01' AS MARPONO, '2' AS MARPOSEQ, 'BBB' AS marhtno, 3 AS marhqty, 1 AS marbqty

       UNION ALL

       SELECT 'PO-131210-RM-01' AS MARPONO, '2' AS MARPOSEQ, 'CCC' AS marhtno, 7 AS marhqty, 1 AS marbqty

       UNION ALL

       SELECT 'PO-131210-RM-01' AS MARPONO, '3' AS MARPOSEQ, 'DDD' AS marhtno, 18 AS marhqty, 0 AS marbqty

)

SELECT (CASE WHEN Num != 1 THEN '' ELSE maqpono END) AS maqpono

       , (CASE WHEN Num != 1 THEN '' ELSE maqposeq END) AS maqposeq

       , (CASE WHEN Num != 1 THEN '' ELSE maqhqty END) AS maqhqty

       , (CASE WHEN Num != 1 THEN '' ELSE maqbqty END) AS maqbqty

       , marhtno, marhqty,  marbqty

FROM

(

       SELECT maqpono, maqposeq, maqhqty, maqbqty, marhtno, marhqty,  marbqty

             , ROW_NUMBER() OVER (PARTITION BY maqpono, maqposeq, maqhqty, maqbqty ORDER BY marhqty) AS Num

       from MA170MP

       JOIN MA180MP ON MAQPONO=MARPONO AND MAQPOSEQ = MARPOSEQ

) AS A

답변 감사 드립니다. 정확히 해결 되었습니다.

글을 읽다가 궁금해서 물어보려고합니다..

향지님 댓글에 보면  FROM 절에  인라인뷰에 ORDER BY 가 있는데요..

제가 책으로 공부했을때는 인라인뷰에는 ORDER BY 가  쓰이면 안된다고 배웠습니다..

그러나 향지님께서 보여주신 예제를 보니 잘되니까요... 

제가 잘못배운건지 혼동이 되어서 여쭙습니다..