private void SuKienLoadForm()
        {
            txtTenKhachHang.Text = "";
            txtDiaChi.Text       = "";
            txtCMND.Text         = "";
            List <KhachHangDTO> lst = CustomerBUS.LayDSLoaiKhach();

            cmbLoaiKhach.Items.Clear();
            for (int i = 0; i < (lst.Count); i++)
            {
                cmbLoaiKhach.Items.Add(lst[i].LoaiKhach);
            }
            cmbPhong.DisplayMember         = "MaPhong";
            cmbPhong.ValueMember           = "MaPhong";
            cmbPhong.DataSource            = RoomBUS.DanhSachPhongDangDuocThue();
            gcDanhSachKhachHang.DataSource = CustomerBUS.DanhSachKhachHang();
        }