private void comboBox1_KeyUp(object sender, KeyEventArgs e)
        {
            Regex rx = new Regex(@"^(0|\+84)\d{9}");

            if (rx.IsMatch(comboBox1.Text))
            {
                DataTable dt = BLL.getDiningTableExixs(comboBox1.Text);
                if (dt.Rows.Count > 0)
                {
                    DataRow row = dt.Rows[0];
                    MaKH.Text   = row["MaKH"].ToString();
                    TenKH.Text  = row["TenKH"].ToString();
                    DiaChi.Text = row["DiaChi"].ToString();
                    //SoDiemTichLuy.Text = row["SoDiemTichLuy"].ToString();
                    NgayGiaNhap.Text        = row["NgayGiaNhap"].ToString();
                    dateTimePicker1.Text    = row["ThoiGianDat"].ToString();
                    dateTimePicker2.Text    = row["ThoiGianTra"].ToString();
                    label2.Text             = row["MaBan"].ToString() + "  ";
                    Bancanxoa.DataSource    = dt;
                    Bancanxoa.DisplayMember = "MaBan";
                }
                else
                {
                    String et = "";


                    MaKH.Text   = "";
                    TenKH.Text  = "";
                    DiaChi.Text = "";
                    //SoDiemTichLuy.Text = row["SoDiemTichLuy"].ToString();
                    NgayGiaNhap.Text        = "";
                    dateTimePicker2.Text    = "";
                    dateTimePicker1.Text    = "";
                    label2.Text             = "";
                    Bancanxoa.DisplayMember = "";
                }
            }
            else
            {
                String et = "";


                MaKH.Text = "";

                TenKH.Text  = "";
                DiaChi.Text = "";
                //SoDiemTichLuy.Text = row["SoDiemTichLuy"].ToString();
                NgayGiaNhap.Text        = "";
                dateTimePicker2.Text    = "";
                dateTimePicker1.Text    = "";
                label2.Text             = "";
                Bancanxoa.DisplayMember = "";
            }
        }