public ActionResult AddStudentToDpt(StudentDepartmentIDs studentDepartmentIDs)
        {
            if (ModelState.IsValid)
            {
                int stId    = studentDepartmentIDs.StudentId;
                var decoded = SecureCodes.Decode(stId.ToString());
                studentDepartmentIDs.StudentId = Convert.ToInt32(decoded);

                db.studentDepartmentIDs.Add(studentDepartmentIDs);
                db.SaveChanges();
                return(Redirect("/students/Index"));
            }
            return(View());
        }