题解 | #最差是第几名(一)#

select grade,
case 
when grade='A' then  (select sum(a.number) 
from (select * from class_grade order by grade limit 1) a)
when grade='B' then (select sum(a.number) 
from (select * from class_grade order by grade limit 2) a)
when grade='C' then (select sum(a.number) 
from (select * from class_grade order by grade limit 3) a)
when grade='D' then (select sum(a.number) 
from (select * from class_grade order by grade limit 4) a)
when grade='E' then (select sum(a.number) 
from (select * from class_grade order by grade limit 5) a)
end as t_rank

from class_grade 
order by grade 
;