WITH TempTable AS (
    SELECT '20250101' AS 날짜, 'A' AS 키, '01' AS 코드1, '02' AS 코드2, NULL AS 코드3
    UNION ALL
    SELECT '20250101', 'B', '01', NULL, '04'
    UNION ALL
    SELECT '20250105', 'A', '05', NULL, NULL
)
SELECT 날짜, 키, 코드
FROM TempTable
UNPIVOT (
    코드 FOR 코드컬럼 IN (코드1, 코드2, 코드3)
) AS unpvt

WITH t AS
(
SELECT '20250101' dt, 'A' ky, '01' cd1, '02' cd2, null cd3 FROM dual
UNION ALL SELECT '20250101', 'B', '01', null, '04' FROM dual
UNION ALL SELECT '20250105', 'A', '05', null, null FROM dual
)
SELECT *
  FROM t
 UNPIVOT(cd FOR gb IN (cd1, cd2, cd3))
;