sql语句怎样写?(在线等待)

[elike]

学生学习数据库结构如下:
table jb_tab{
xm char(8), //姓名
xb char(1), //性别
c_num //课程号
}
要查询学生学习两门以上姓名的SQL语句.

[purplecowry22]

select xm
from jb_tab
where having count(c_num)>2;
试试看，我记不太清了

[success_victory]

select xm
from jb_tab
group by xm
having count(c_num)>2;

[hycao]

select xm, xb, count(c_num) as total_num from jb_tab group by xm, xb having count(c_num) > 2

[purplecowry22]

success_victory的是对的，我认为