select
    t.name,
    t.grade_num
from
(select
    u.name as name,
    sum(g.grade_num) as grade_num
from 
    user u
right join
    grade_info g
on 
    u.id=g.user_id
where
    g.type = 'add'
group by
    u.name) t
order by
    t.grade_num desc
limit 1