如何为查询mysql添加临时值

Question

我的数据库中有以下查询，我想添加一个新列来处理学生的最终上诉：查询：

select student_name,q4.percentage
from (select q2.student_id,mark *100/total as Percentage
from (select class_id,sum(max_mark)as total
from course
group by(class_id)
)q1 ,
(select sum(mark) as mark,student_id
from grades
group by(student_id)
) q2
where q2.student_id in (select student_id
from student
where student.section_id in(select section_id 
from section 
where class_id=q1.class_id)
)
order by q2.student_id
) q4
inner join student on q4.student_id=student.student_id;

结果如下：在此处输入图像描述

STUDENT_NAME	百分比
Massoud	50.41667
Ali Shbeeb	84.16667
Mona	75.2941

您可以包含一列带有如下case语句的列-

select student_name,q4.percentage,
CASE WHEN q4.percentage > 80 THEN 'A'
WHEN q4.percentage > 60 THEN 'B'
WHEN q4.percentage > 40 THEN 'C'
ELSE 'E'
END award
from (select q2.student_id,mark *100/total as Percentage
from (select class_id,sum(max_mark)as total
from course
group by(class_id)
)q1 ,
(select sum(mark) as mark,student_id
from grades
group by(student_id)
) q2
where q2.student_id in (select student_id
from student
where student.section_id in(select section_id 
from section 
where class_id=q1.class_id)
)
order by q2.student_id
) q4
inner join student on q4.student_id=student.student_id;