select class from (
select class,sum(decode(sex),'M',1,0) Male,sum(decode(sex),'F',1,0) Female from schools group by class)
where Male=Female;
select class,sum(decode(sex),'M',1,0) Male,sum(decode(sex),'F',1,0) Female from schools group by class)
where Male=Female;
so the data type of field sex can be changed into CHAR(1).
select class,case when sex='M' then count(sex) end male,
case when sex='F' then count(sex) end female
from schools group by class,sex)
group by class having sum(male)=sum(female);
select class,sum(decode(sex,'M',1,0)) Male,sum(decode(sex,'F',1,0)) Female from schools
group by class)
where Male=Female;