Select all rows of all pages in ASP.Net GridView using CheckBox

Check this example

 Check All<asp:CheckBox ID="chkAll" runat="server" AutoPostBack = "true" />
    <asp:GridView ID="GridView1" runat="server" OnRowDataBound = "OnRowDataBound" AllowPaging="true" AutoGenerateColumns = "false" OnPageIndexChanging="OnPageIndexChanging">
        <Columns>
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:CheckBox ID="CheckBox1" runat="server" />
                </ItemTemplate>
            </asp:TemplateField>
            <asp:BoundField DataField="ContactName" />
        </Columns>
    </asp:GridView>

   protected void OnPageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        GridView1.PageIndex = e.NewPageIndex;
        GridView1.DataBind();
    }
    protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            (e.Row.FindControl("CheckBox1") as CheckBox).Checked = chkAll.Checked;
        }
    }
    protected void Page_Load(object sender, EventArgs e)
    {

        string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        string query = "SELECT ContactName FROM Customers";
        SqlCommand cmd = new SqlCommand(query);
        using (SqlConnection con = new SqlConnection(conString))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using (DataSet ds = new DataSet())
                {
                    sda.Fill(ds);
                    GridView1.DataSource = ds;
                    GridView1.DataBind();
                }
            }
        }
}