找到具有最大平均分数的学生

Question

我尝试了很多但没有成功，我想只显示学生名单中学生分数的最大平均值，如下表所示。

我的表

我想得到如下结果

预期输出

到目前为止我做了什么

SELECT MAX(a.Total_Qty) As TotalMax,a.studentId
FROM(
SELECT AVG( s.marks ) AS Total_Qty,s.studentId
FROM results s
WHERE s.stream = 'Form One'
GROUP BY s.studentId) AS a

Answer 1

内部查询将为您提供每个学生的平均值列表。 然后我们按其平均分数（降序）排序，最后得到前1名（限制1）

SELECT  a.studentId, a.Total_Qty as MaxAvg
FROM(

   SELECT AVG( s.marks ) AS Total_Qty,s.studentId
   FROM results s
   WHERE s.stream = 'Form One'  
   GROUP BY s.studentId)

 AS a
 Order by a.Total_Qty Desc
 Limit 1

可替换地：

   SELECT AVG( s.marks ) AS Total_Qty,s.studentId
   FROM results s
   WHERE s.stream = 'Form One'  
   GROUP BY s.studentId
   Order By AVG( s.marks ) Desc
   Limit 1

Answer 2

（UNTESTED）我希望有所帮助

如果您使用的是MSSQL：

SELECT TOP(1) studentId, AVG(marks) FROM results GROUP BY studentId
ORDER BY MAX(AVG(marks)) Desc

如果您使用的是SQL：

SELECT studentId, AVG(marks) FROM results GROUP BY studentId
ORDER BY MAX(AVG(marks)) Desc Limit 0,1