public ActionResult AddStudentToClass(int studentId, int classId)
        {
            ClassStudent cs = new ClassStudent();
            cs.StudentID = studentId;
            cs.ClassID = classId;

            db.ClassStudents.Add(cs);
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        public ActionResult ApproveAddRequest(int id)
        {
            AddRequest ar = db.AddRequests.Find(id);
            ar.Processed = true;

            ClassStudent cs = new ClassStudent();
            cs.ClassID = ar.ClassID;
            cs.StudentID = ar.StudentID;
            db.ClassStudents.Add(cs);

            db.Entry(ar).State = System.Data.Entity.EntityState.Modified;
            db.SaveChanges();

            return RedirectToAction("ApproveAddRequest");
        }
        public ActionResult AddStudentToClass(int studentId, int classId)
        {
            ClassStudent check = (from m in db.ClassStudents
                                  where m.ClassID == classId &&
                                    m.StudentID == studentId
                                  select m).FirstOrDefault();
            if (check == null)
            {
                ClassStudent add = new ClassStudent();
                add.ClassID = classId;
                add.StudentID = studentId;

                db.ClassStudents.Add(add);

                db.SaveChanges();
            }

            return RedirectToAction("Index");
        }