sql查询

 select cTitle,sGender,COUNT(*)
 from StudentInfo stu
 inner join ClassInfo class on stu.cid=class.cId
 group by cTitle,sGender

 --班级 男生  女生
 --青龙 1     2
 create view Student_Class_Gender
 as
 select cTitle,sGender,COUNT(*) as count1
 from StudentInfo stu
 inner join ClassInfo class on stu.cid=class.cId
 group by cTitle,sGender

 select cTitle,
 max( case sGender when 1 then count1 else 0 end) 男,
 max( case when sGender=0 then count1 else 0 end) 女
 from Student_Class_Gender
 group by cTitle

结果为: