.net DataGrid绑定列手动添加数据

前台DataGrid：

        <asp:DataGrid ID="Data" runat="server" AutoGenerateColumns="False" CellPadding="0"
            Font-Bold="False" OnItemCommand="Data_ItemCommand" OnItemDataBound="Data_ItemDataBound"
            PageSize="5" Width="100%">
            <Columns>
                    <asp:BoundColumn DataField="aaa"></asp:BoundColumn>
                    <asp:BoundColumn DataField="bbb"></asp:BoundColumn>
                    <asp:BoundColumn DataField="ccc"></asp:BoundColumn>
            </Columns>
        </asp:DataGrid>

后台cs：

        DataTable dt = new DataTable();
       
        dt.Columns.Add("aaa");
        dt.Columns.Add("bbb");
        dt.Columns.Add("ccc");

        dt.Rows.Clear();
        DataRow dr = dt.NewRow();

        dr[0] = "aaaaa";
        dr[1] = "bbbbb";
        dr[2] = "ccccc";

        dt.Rows.InsertAt(dr,0);
        axDgdData.DataSource = dt;
        axDgdData.DataBind();

        int i = dt.Columns.Count;
        Response.Write(i.ToString());