Oracle有一张表info,有三列,学校(school),班级(class),学生姓名(name),有全市所有的学校?
1、每个班级有多少学生并按学生数量排序。 select school,class,count(1) from info group by school,class order by 3;2、取20~30个学生的班级:select school,class,count(1) from info group by school,class having (count(1) >=20 and count(1) =<30 ) order by 3 ;。
1、每个班级有多少学生并按学生数量排序。
select school,class,count(1) from info group by school,class order by 3;2、取20~30个学生的班级:select school,class,count(1) from info group by school,class having (count(1) >=20 and count(1) =<30 ) order by 3 ;。收起