Anxious, this SQL will not be written, please help me see how to write it?

2749070

A table has three fields: a, b, and c. When b is empty, the meaning of a is "A". When b is not empty, the meaning of a is "B". Now I want Take out these two meanings at the same time and group them in C. How to take them?
I.e. the result column I took should be:
field c sum of field a representing "A" sum of field a representing "B"
c1 a1 a11
c2 a2 a22


By the way, my database is sysbase

baobaoly01

select
  c,
  sum (case when b is null then 1 else 0 end) A,
  sum (case when b is not null then 1 else 0 end) B
from
  yourtable
group by
  c

2749070

Thanks. . . .