public void HienThiDanhSach()
        {
            string macongty    = Session["congty"].ToString();
            string manguoidung = Session["user"].ToString();

            string ngonngu = Session["languege"].ToString();

            if (ngonngu == "lbl_VN")
            {
                GridView1.DataSource = db.DanhSachPhieuDaGuiBiHuyTheoNguoiTao(manguoidung, macongty);
                GridView1.DataBind();
            }
            else if (ngonngu == "lbl_TW")
            {
                GridView2.DataSource = db.DanhSachPhieuDaGuiBiHuyTheoNguoiTaoTW(manguoidung, macongty);
                GridView2.DataBind();
            }
            else if (ngonngu == "lbl_EN")
            {
                GridView1.DataSource = db.DanhSachPhieuDaGuiBiHuyTheoNguoiTao(manguoidung, macongty);
                GridView1.DataBind();
            }
        }