注意を考慮したうえでの計算で求める総積

こんな感じ？

WITH
  Input(id, n) AS (
    SELECT 1, 1
    UNION ALL SELECT 1, 2
    UNION ALL SELECT 1, 3
    UNION ALL SELECT 1, 0
    
    UNION ALL SELECT 2, 1
    UNION ALL SELECT 2, -2
    UNION ALL SELECT 2, -3
    
    UNION ALL SELECT 3, 1
    UNION ALL SELECT 3, -2
    UNION ALL SELECT 3, 3
  )
SELECT
    id
  , CASE
    WHEN SUM(CASE n WHEN 0 THEN 1 ELSE 0 END) >= 1
      THEN 0
      ELSE CASE SUM(CASE WHEN n < 0 THEN 1 ELSE 0 END) % 2
           WHEN 1 THEN -EXP(SUM(LOG(NULLIF(ABS(n), 0))))
                  ELSE  EXP(SUM(LOG(NULLIF(ABS(n), 0))))
           END
    END AS n
FROM
    Input
GROUP BY
    id
ORDER BY
    id

結果は、

id	n
1	0
2	6
3	-6

こう。