private void btroom106_Click(object sender, EventArgs e)
        {
            frmDatPhong fbook = new frmDatPhong();

            this.Hide();
            fbook.ShowDialog();
        }
        private void btroom104_Click(object sender, EventArgs e)
        {
            Phong p = (from n in db.Phongs
                       where n.MaPhong == "P004"
                       select n).SingleOrDefault();
            DatPhong dp = (from n in db.DatPhongs
                           where n.MaPhong == "P004" && n.TinhTrangThanhToan == "Chua Thanh Toan"
                           select n).SingleOrDefault();

            if (btnP104.BackColor == Color.Green)
            {
                frmDatPhong fbook = new frmDatPhong(p, nhanVien);
                this.Hide();
                fbook.ShowDialog();
            }
            else
            {
                frmThanhToan fthanhtoan = new frmThanhToan(dp, nhanVien);
                this.Hide();
                fthanhtoan.ShowDialog();
            }
        }