5개 max인가요? 

컬럼을 가변적으로 가져가기는 힘듭니다.

다이나믹 쿼리를 사용하시거나

컬럼 갯수를 고정값을 이용해서 사용하시거나

컬럼에 구분자를 넣어서 어플리케이션에서 나눠어서 사용하던가 하셔야합니다.

WITH t AS
(
SELECT 5236794 num_cd, '기타' gubun, 'G1' gubun_code, '5-A' class FROM dual
UNION ALL SELECT 5236794, '피아노', 'P1', '5-A' FROM dual
UNION ALL SELECT 5236794, '피아노', 'P1', '7-A' FROM dual
UNION ALL SELECT 5236794, '트럼펫', 'T1', '2-A' FROM dual
UNION ALL SELECT 5236794, '섹소폰', 'S1', '3-A' FROM dual
UNION ALL SELECT    3456, '기타'  , 'G1', '1-A' FROM dual
UNION ALL SELECT    3456, '피아노', 'P1', '5-A' FROM dual
)
SELECT num_cd
     , MIN(DECODE(rn, 1, gbn)) gbn1
     , MIN(DECODE(rn, 1, cod)) cod1
     , MIN(DECODE(rn, 1, cls)) cls1
     , MIN(DECODE(rn, 2, gbn)) gbn2
     , MIN(DECODE(rn, 2, cod)) cod2
     , MIN(DECODE(rn, 2, cls)) cls2
     , MIN(DECODE(rn, 3, gbn)) gbn3
     , MIN(DECODE(rn, 3, cod)) cod3
     , MIN(DECODE(rn, 3, cls)) cls3
     , MIN(DECODE(rn, 4, gbn)) gbn4
     , MIN(DECODE(rn, 4, cod)) cod4
     , MIN(DECODE(rn, 4, cls)) cls4
     , MIN(DECODE(rn, 5, gbn)) gbn5
     , MIN(DECODE(rn, 5, cod)) cod5
     , MIN(DECODE(rn, 5, cls)) cls5
     , MIN(DECODE(rn, 6, gbn)) gbn6
     , MIN(DECODE(rn, 6, cod)) cod6
     , MIN(DECODE(rn, 6, cls)) cls6
     , MIN(DECODE(rn, 7, gbn)) gbn7
     , MIN(DECODE(rn, 7, cod)) cod7
     , MIN(DECODE(rn, 7, cls)) cls7
  FROM (SELECT num_cd
             , gubun      gbn
             , gubun_code cod
             , class      cls
             , ROW_NUMBER() OVER(PARTITION BY num_cd ORDER BY '정렬기준') rn
          FROM t
        )
 GROUP BY num_cd
;

한 컬럼으로 받아서 split 해서 쓰시려면

http://www.gurubee.net/article/55512