如何在sql和php中填写最小值？

Question

我在SQL的表：

表1

date  name s1 s2 s3 s4 min_value 
7/10/2017 ram 10 11 12 13 11 
7/10/2017 tom 17 16 15 14 16 
7/10/2017 ara 13 9 26 22 9 

如果I总的所有字段在单个日期然后

s1 total value 40 
s2 total value 36 
s3 total value 53 
s4 total value 49 

这里minimum value被36.这意味着minimum value列是s2 。

我在min_value字段中分别插入了s2字段值。

我的问题是how will I fill min_value field?

请帮助我。

在此先感谢。

Answer 1

这里的代码来实现这一目标：

SELECT [date], s1, s2, s3, s4, 
    case when s1 < s2 and s1 < s3 and s1 < s4 then s1 
     when s2 < s1 and s2 < s3 and s2 < s4 then s2 
     when s3 < s1 and s3 < s2 and s3 < s4 then s3 
     else s4 end as [min_value] 
FROM (
    SELECT [date], sum(s1) AS s1, sum(s2) AS s2, sum(s3) AS s3, sum(s4) AS s4 FROM [Table1] 
    GROUP BY [date] 
) AS A