如何获取mysql中“标记”列的百分比

Question

这是我的桌子：

我试试这个代码：

SELECT student_name, (marks)*100/(SELECT SUM(marks) as 'totalmarks') 
from tbl_marks 
GROUP BY student_name

我得到了这个结果：

Answer 1

我认为你想要：

select m.student_name, m.marks * 100 / t.marks as percent_overall
from (select student_name, sum(marks) marks from tbl_marks group by student_name) m
cross join (select sum(marks) marks from tbl_marks) t

这也可以用窗口函数来表达，比如：

select 
    student_name,
    sum(marks) * 100 / (sum(sum(marks)) over()) percent_overall
from tbl_marks
group by student_name