public void AddNewUser(User user)
 {
     using (var context = new ShoppingWebDBEntities())
     {
         context.AddToUsers(user);
         context.SaveChanges();
     }
 }
 public void AppendPoint(string userName, int point)
 {
     using (var context = new ShoppingWebDBEntities())
     {
         var user = FindByUserName(userName);
         if (user == null) return;
         user.Point += point;
         context.Update(user);
         context.SaveChanges();
     }
 }