private void EditRoom()
        {
            SelectedRoom.Capacity     = Int32.Parse(Capacity);
            SelectedRoom.Description_ = Description;
            DataProvider.Ins.DB.SaveChanges();

            var temp   = SelectedRoom;
            int length = ListRoom.Count();

            for (int i = 0; i < length; i++)
            {
                if (ListRoom[i].RoomID == SelectedRoom.RoomID)
                {
                    ListRoom.RemoveAt(i);
                    ListRoom.Insert(i, temp);
                    break;
                }
            }

            SelectedRoom = temp;
        }
        private void DeleteRoom()
        {
            // check if not used anymore first
            if (IsNotUsing())
            {
                SelectedRoom.Status_ = "Không còn sử dụng";
                DataProvider.Ins.DB.SaveChanges();

                var temp = SelectedRoom;
                for (int i = 0; i < ListRoom.Count(); i++)
                {
                    if (ListRoom[i].RoomID == SelectedRoom.RoomID)
                    {
                        ListRoom.RemoveAt(i);
                        ListRoom.Insert(i, temp);
                        break;
                    }
                }
            }
            else
            {
                MessageBox.Show("Phong dang duoc su dung");
            }
        }