下面是学生表的结构：
rollno number(4)
name varchar(20)
course varchar(20)
要显示注册学生人数超过 5 人的课程，应如何查询？( )
Select course from students where count(course) > 5;
Select course from students where count(*) > 5 group by course;
Select course from students group by course;
Select course from students group by course having count(*) > 5;
