加權平均在MySQL

Question

我目前使用下面的查詢，以獲得最高平均結果：

select ContentType, AVG(Result) as AvgContent from dopractice where S_Id =@S_Id group by ContentType order by 2 desc limit 1; 

我想修改我的查詢來計算最高加權平均值。

例如：

((X*1)+(Y*2)+(Z*3))/3 

有沒有辦法做到這一點使用一個查詢？

注：dopractice表中的列(Id, StudentId, LessonId, ContentType, result, Date)

Answer 1

試試這個代碼。可能會對你有幫助。

select temp.content,MAX(temp.AvgContent) 
    FROM 
    (
    select ContentType AS content, AVG(Result) as AvgContent 
    from dopractice 
    where StudentId = @S_Id 
    group by ContentType order by ContentType desc 
    ) AS temp 
    group by temp.ContentType;