public int addstudent(string stunum, string sname, int gender, string startyear, int collegeid)
 {
     UserService userService = new UserService();
     int uid, sid = 0;
     uid = userService.insert(stunum, "123456", 1);
     if (uid != 0)
     {
         StudentService studentService = new StudentService();
         sid = studentService.insert(uid, stunum, sname, gender, startyear, collegeid);
     }
     return sid;
 }