/*========================================
* 컬럼1이 계산 기준이라고 할 경우
*========================================*/
SELECT COL1
, COL2
, COL2 / LEAD(COL2) OVER(ORDER BY COL1) AS COL3
FROM (SELECT 'A' AS COL1, 10 AS COL2 FROM DUAL UNION ALL
SELECT 'B' AS COL1, 20 AS COL2 FROM DUAL
)