[Web,C#] ต้องการ Pass Value ไปหน้าที่ 1 แล้วกดปุ่มในหน้าที่ 1 ส่งต่อไปหน้าที่ 2 ค่ะ

<script runat="server">

    String strConnString = WebConfigurationManager.ConnectionStrings["MDSConnectionString"].ConnectionString;
        
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["strUser"] == null)
        {
            Response.Redirect("~/index.aspx");
            Response.End();
        }
        else if (!IsPostBack)
        {
            lblIDser.Text = Request.QueryString["id_nob"];
            BindContrydropdown1();
            BindContrydropdown2();
            BindData();
            this.btnOK = btnOK;
        }        
    }
        
    protected void BindContrydropdown1()
    {
        using (SqlConnection con = new SqlConnection(strConnString))
        {
            con.Open();
            
            SqlCommand cmd = new SqlCommand("Select id_itemtype,itemtype FROM dbo.tbl_itemtype WHERE archive_date IS NULL", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);

            ddlDep.DataSource = ds;
            ddlDep.DataTextField = "itemtype";
            ddlDep.DataValueField = "id_itemtype";
            ddlDep.DataBind();
            con.Close();
        }
    }

    protected void BindContrydropdown2()
    {
        using (SqlConnection con = new SqlConnection(strConnString))
        {
            con.Open();
            string sqlStatement = "SELECT id_item + ' / ' + item AS item, id_item FROM dbo.tbl_item WHERE archive_date IS NULL";
            SqlCommand cmd = new SqlCommand(sqlStatement, con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);

            ddlMachine.DataSource = ds;
            ddlMachine.DataTextField = "item";
            ddlMachine.DataValueField = "id_item";
            ddlMachine.DataBind();
            con.Close();
        }
    }

    protected void BindData()
    {
        DataTable dt = new DataTable();
        SqlConnection con = new SqlConnection(strConnString);
        con.Open();
        SqlCommand cmd = new SqlCommand("SELECT dt_to,id_cu,id_item,txt,dt_sa,ti_sa from dbo.tbl_blue WHERE id_nob = '" + lblIDser.Text + "'", con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);

        da.Fill(dt);
        if (dt.Rows.Count > 0)
        {
            lblDate.Text = dt.Rows[0]["dt_to"].ToString();
            lblDate.Text = dt.Rows[0].Field<DateTime>(0).ToString("yyyy-MM-dd");
            txtSerList.Text = dt.Rows[0]["txt"].ToString();
            ddlDep.SelectedValue = dt.Rows[0]["id_cu"].ToString();
            ddlMachine.SelectedValue = dt.Rows[0]["id_item"].ToString();
            txtDtsa.Text = dt.Rows[0]["dt_sa"].ToString();
            txtDtsa.Text = dt.Rows[0].Field<DateTime>(4).ToString("yyyy-MM-dd");
            txtTisa.Text = dt.Rows[0]["ti_sa"].ToString();
        }
        con.Close(); 
    }
    void btnOK_Click(Object sender, EventArgs e)
    {

        SqlConnection con = new SqlConnection(strConnString);
        SqlCommand cmd = new SqlCommand();
        String strSQL;

        strSQL = "UPDATE dbo.tbl_blue SET " +
            " id_cu = '" + ddlDep.SelectedItem.Value + "'" +
            " ,id_item = '" + ddlMachine.SelectedItem.Value + "'" +
            " ,txt = '" + txtSerList.Text + "'" +
            " ,dt_sa = '" + txtDtsa.Text + "'" +
            " ,ti_sa = '" + txtTisa.Text + "'" +
            " WHERE id_nob = '" + lblIDser.Text + "'";

        Session["strIDser"] = lblIDser.Text;  
        Session["strDep"] = ddlDep.SelectedItem.Text;
        Session["strMachine"] = ddlMachine.SelectedItem.Text;
        Session["strSerlist"] = txtSerList.Text;
        Session["strDtsa"] = txtDtsa.Text;
        Session["strTisa"] = txtTisa.Text;
        
        con.ConnectionString = strConnString;
        con.Open();
        cmd.Connection = con;
        cmd.CommandText = strSQL;
        cmd.CommandType = CommandType.Text;

        try
        {
            cmd.ExecuteNonQuery();
            Response.Redirect("~/service/fr_eservice2.aspx");
            //this.lblStatus.Visible = true;
            //this.lblStatus.Text = "บันทึกการแก้ไขใบแจ้งซ่อมสำเร็จ";
        }
        catch (Exception ex)
        {
            this.lblStatus.Visible = true;
            this.lblStatus.Text = "Record can not insert Error (" + ex.Message + ")";
        }

        con.Close();
        con = null;

    }

    protected void btnDel_Click(object sender, EventArgs e)
    {
        String strSQL;       
        strSQL = "SELECT b.id_nob INTO #RecordsToDelete FROM dbo.tbl_blue b JOIN dbo.tbl_yellow y ON b.id_nob = y.id_noy WHERE b.id_nob = '" + lblIDser.Text + "' DELETE FROM dbo.tbl_blue WHERE id_nob IN (SELECT id_nob FROM #RecordsToDelete) DELETE FROM dbo.tbl_yellow WHERE id_noy IN (SELECT id_nob FROM #RecordsToDelete)";        
        SqlConnection con = new SqlConnection(strConnString);
        SqlCommand cmd = new SqlCommand(strSQL, con);
        
        try
        {
            con.Open();
            cmd.ExecuteNonQuery();
            this.lblStatus.Visible = true;
            this.lblStatus.Text = "Record deleted.";
        }
        catch (Exception ex)
        {
            this.lblStatus.Visible = true;
            this.lblStatus.Text = "Record can not delete Error (" + ex.Message + ")";
        }

        con.Close();
        con = null;
    }
</script>