public ActionResult Index()
 {
     var model = new KhachHangViewModel
     {
         KhachHangs = storeDB.KhachHangs.ToList<KhachHang>(),
         SoLuong = storeDB.KhachHangs.Count()
     };
     return View(model);
 }
        public ActionResult Delete(int id, FormCollection collection)
        {
            KhachHang existKH = storeDB.KhachHangs
                .Where(k => k.Id == id)
                .SingleOrDefault();
            storeDB.KhachHangs.DeleteObject(existKH);
            storeDB.SaveChanges();


            var result = new KhachHangViewModel
            {
                KhachHangs = storeDB.KhachHangs.ToList<KhachHang>(),
                SoLuong = storeDB.KhachHangs.Count(),
                DeleteId = id
            };
            return Json(result);
        }