题解 | #获得积分最多的人(三)#

select user.id as id, name, grade_num
from
(select user_id, grade_num
from
(select user_id, sum(grade_num) as grade_num
from
(select user_id, (case when type = 'add' then grade_num * 1 else grade_num * -1 end) as grade_num
from grade_info) as new1
group by user_id) as new3 
where grade_num = 
(select max(grade_num) as grade_num
from 
(select user_id, sum(grade_num) as grade_num
from
(select user_id, (case when type = 'add' then grade_num * 1 else grade_num * -1 end) as grade_num
from grade_info) as new1
group by user_id) as new2)) as new4 left join user on new4.user_id = user.id