protected void btnCapNhat_Click(object sender, EventArgs e)
        {
            try
            {
                int ma = int.Parse(txtMaS.Text);
                string ten = txtTenS.Text;
                string dt = txtDtS.Text;
                string email = txtEmailS.Text;
                string diachi = txtDiaChiS.Text;
                int chucvu = int.Parse(drChucVuS.SelectedValue.ToString());
                string un = txtUsernameS.Text;
                float rate = float.Parse(txtRateU.Text);
                string maten = txtMaTenS.Text;
                int kh = int.Parse(txtKichHoat.Text);
                int pub = int.Parse(txtPublic.Text);
                GiamDinhVienDAO gdvdao = new GiamDinhVienDAO();
                string tenfull = txtFullnameS.Text;
                gdvdao.SuaGDV(ma, ten, dt, email, diachi, chucvu, un, maten, kh, pub, rate, tenfull);
                HienThiDanhSach();
                sua.Visible = false;

            }
            catch (Exception ex)
            {
                Response.Write("<script> alert('Không để trống thông tin!');</script>");
            }
        }