mvc DropDownList默认选项

  DDDContext db = new DDDContext();
            List<SelectListItem> selectlistDistrict = new List<SelectListItem>();
            foreach (var s in db.Department)
            {
                if (s.Name=="人事部")
                {
                    selectlistDistrict.Add(new SelectListItem()
                    {
                        Text = s.Id.ToString(),
                        Value = s.Name,
                        Selected = true
                    });
                }
                else
                {
                    selectlistDistrict.Add(new SelectListItem()
                    {
                        Text = s.Id.ToString(),
                        Value = s.Name,
                     
                    });
                }
            }
            ViewBag.select = selectlistDistrict;