请教一个统计的sql写法

Question

select class,count(decode('A',1,0)) A,count(decode('B',1,0)) B,
count(decode('C',1,0)) C,count(decode('D',1,0)) D,count(decode('E',1,0)) E
from tbname group by class;

Answer 1

select class,sum(decode(,'A',1,0)) A,sum(decode(,'B',1,0)) B,
sum(decode(,'C',1,0)) C,sum(decode(,'D',1,0)) D,sum(decode(,'E',1,0)) E
from tbname group by class;

Answer 2

backham的ok
decode漏了''参数。

Answer 3

select class,sum(decode(,'A',1,0)) A,sum(decode(,'B',1,0)) B,
sum(decode(,'C',1,0)) C,sum(decode(,'D',1,0)) D,sum(decode(,'E',1,0)) E
from tbname group by class;