public static string DangNhap(string taikhoan, string matkhau)
    {
        bus_Danhmuc dm = new bus_Danhmuc();
        int         kq = dm.BUS_DANGNHAP(taikhoan, matkhau);

        return(Convert.ToString(kq));
    }
    public static string DangNhap(string taikhoan, string matkhau)
    {
        bus_Danhmuc dm = new bus_Danhmuc();
        int         kq = dm.BUS_DANGNHAP(taikhoan, matkhau);

        HttpContext.Current.Session.Add("user", taikhoan);
        return(Convert.ToString(kq));
    }