꿈라CBT다음 T 테이블에 대해 SQL을 실행한 결과를 ID 순서로 나타낸 것으로 가장 적절한 것은?
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T 테이블
| ID | GRP | VAL |
|---|---|---|
| 1 | 1 | 10 |
| 2 | 1 | 20 |
| 3 | 2 | 30 |
| 4 | 2 | 40 |
| 5 | 3 | 50 |
SELECT ID,
MAX(VAL) OVER () AS M,
SUM(VAL) OVER (ORDER BY GRP) AS S,
FIRST_VALUE(VAL) OVER (
ORDER BY ID
ROWS BETWEEN 1 PRECEDING AND CURRENT ROW
) AS F
FROM T
ORDER BY ID;- 1M = (50, 50, 50, 50, 50), S = (30, 30, 100, 100, 150), F = (10, 10, 20, 30, 40)
- 2M = (50, 50, 50, 50, 50), S = (10, 30, 60, 100, 150), F = (10, 10, 20, 30, 40)
- 3M = (50, 50, 50, 50, 50), S = (30, 30, 100, 100, 150), F = (NULL, 10, 20, 30, 40)
- 4M = (10, 20, 30, 40, 50), S = (30, 30, 100, 100, 150), F = (10, 10, 20, 30, 40)