让我说我有这样的一列的表:
@H_502_2@Col A
1
2
3
4
如果我SUM它,那么我会得到这个:
@H_502_2@Col A 10我的问题是:我如何乘坐Col A,所以我得到以下?
@H_502_2@Col A 24解决方法
使用ROUND,EXP,SUM和LOG的组合
@H_502_2@SELECT ROUND(EXP(SUM(LOG([Col A]))),1)
FROM yourtable
sql小提琴:http://sqlfiddle.com/#!3/d43c8/2/0
说明
LOG返回col a ex的对数. LOG([Col A])返回
@H_502_2@0 0.6931471805599453 1.0986122886681098 1.3862943611198906然后使用SUM将它们全部添加到返回的SUM(LOG([Col A]))中
@H_502_2@3.1780538303479453然后使用EXP(SUM(LOG([‘3.1780538303479453’]))计算该结果的指数,其返回
@H_502_2@23.999999999999993然后用ROUND ROUND(EXP(SUM(LOG(‘.999999999999993’))),1)得到24
额外的答案
简单解决方案:
An invalid floating point operation occurred.
当您的数据中有0时
@H_502_2@SELECT ROUND(EXP(SUM(LOG([Col A]))),1) FROM yourtable WHERE [Col A] != 0如果你只有0,那么上面会给出一个NULL的结果.
@H_502_2@SELECT (ROUND(exp(SUM(log(CASE WHEN[Col A]<0 THEN [Col A]*-1 ELSE [Col A] END))),1)) * (CASE (SUM(CASE WHEN [Col A] < 0 THEN 1 ELSE 0 END) %2) WHEN 1 THEN -1 WHEN 0 THEN 1 END) AS [Col A Multi] FROM yourtableWhen you have negative numbers in your data set.
示例输入:
@H_502_2@1 2 3 -4输出:
@H_502_2@Col A Multi -24