[英]SQL Query to find the product of values in same column
面試問題之前問過。
給定一個包含boxName和value列的表,找到每個框的音量。 值字段具有立方體的長度,bredth和高度。 我需要乘以所有樹的尺寸。
如果需要計算總和,我可以使用groupby ,但此處需要產品
box1 = 12*13*1 = 156
box2 = 1*23*6 = 138
box3 = 12*1*20 = 240
+---------+-------+
| boxName | value |
+---------+-------+
| box1 | 12 |
| box1 | 13 |
| box1 | 3 |
| box2 | 1 |
| box2 | 23 |
| box2 | 6 |
| box3 | 12 |
| box3 | 1 |
| box4 | 30 |
+---------+-------+
嘗試這個
select EXP(SUM(LN(value))) As Product_val ,boxName
from yourTable
Group by boxName
注意: value <= 0
LOG將失敗。
當你有值<= 0時,請使用它。
SELECT
boxName,
CASE
WHEN MinVal = 0 THEN 0
WHEN Neg % 2 = 1 THEN -1 * EXP(ABSMult)
ELSE EXP(ABSMult)
END
FROM
(
SELECT
boxName,
--log of +ve row values
SUM(LN(ABS(NULLIF(Value, 0)))) AS ABSMult,
--count of -ve values. Even = +ve result.
SUM(SIGN(CASE WHEN Value < 0 THEN 1 ELSE 0 END)) AS Neg,
--anything * zero = zero
MIN(ABS(Value)) AS MinVal
FROM
yourTable
GROUP BY
boxName
) foo
提到這個答案
如果您知道每個框對於3個維度將具有正好3行,則可以使用row_number()
分析函數來唯一標識3個維度,然后使用max(case ...)
來提取3個維度並乘以它們:
select boxName,
max(case when rn = 1 then value end) *
max(case when rn = 2 then value end) *
max(case when rn = 3 then value end) as volume
from (select t.*,
row_number() over (partition by t.boxName order by null) as rn
from yourTable t)
group by boxName
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