增加学生信息、删除学生信息、修改学生信息 查询时可实现按姓名查询、按学号查询； 能对用户指定的任意课程名，按成绩升序或降序排列学生数据并显示排序结果-Increase student information, student information delete, modify student information inquiries can be realized by name inquiries, according to study its inquiries can be