how to add dropdownlist on same class in MVC3

   public int EmployeeID { get; set; }
   public string EmpNo { get; set; }
   public string EmployeeACN { get; set; }
   public string EmployeeName { get; set; }
   public Nullable<int> DeptID { get; set; }
   public Nullable<int> DesID { get; set; }
   public string ReportingTo { get; set; }
   public string MailId { get; set; }

public virtual Department Department { get; set; }
   public virtual Designation Designation { get; set; }

// GET: /Employee/Edit/5
 
        public ActionResult Edit(int id)
        {
            Employee employee = db.Employees.Find(id);
            ViewBag.DeptID = new SelectList(db.Departments, "DeptID", "DeptShortDesc", employee.DeptID);
            ViewBag.DesID = new SelectList(db.Designations, "DesID", "ShortDesc", employee.DesID);
            
            return View(employee);
        }

        //
        // POST: /Employee/Edit/5

        [HttpPost]
        public ActionResult Edit(Employee employee)
        {
            if (ModelState.IsValid)
            {
                db.Entry(employee).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            ViewBag.DeptID = new SelectList(db.Departments, "DeptID", "DeptShortDesc", employee.DeptID);
            ViewBag.DesID = new SelectList(db.Designations, "DesID", "ShortDesc", employee.DesID);
          
            return View(employee);
}

ViewBag.EmpNo = new SelectList(db.Employees, "EmpNo", "EmployeeName", employee.EmpNo);

<div class="editor-label">
            @Html.LabelFor(model => model.EmpNo,"ReportingTo")
        </div>
        <div class="editor-field">
            @Html.DropDownList("EmpNo", String.Empty)
            @Html.ValidationMessageFor(model => model.EmpNo)
        </div>