private void LoadNguoiDung()
{
XuLyNguoiDung xl = new XuLyNguoiDung();
ddlChuyenMuc.DataSource = xl.ListNguoiDung();
ddlChuyenMuc.DataValueField = "IDNguoiDung";
ddlChuyenMuc.DataTextField = "TenDangNhap";
ddlChuyenMuc.DataBind();
}
