select studentname,sum(grade),max(col1),max(col2),...max(coln) from tb group by studentname
select studentname,col1,col2,..., --写全字段,除了grade (select sum(grade) from tb where studentname=a.studentname) as grade from tb a where not exists ( select 1 from tb where studentname=a.studentname and key<a.key )
from tb
group by studentname
(select sum(grade) from tb where studentname=a.studentname) as grade
from tb a
where not exists (
select 1 from tb
where studentname=a.studentname
and key<a.key
)