GridView三层嵌套

<form id="form1" runat="server">
    <div>
    <asp:GridView ID="GridViewDiv" runat="server" AutoGenerateColumns="false" DataKeyNames="DivID" DataSourceID="AccessDataSourceDiv" AllowPaging="true" AllowSorting="true" PageSize="1" GridLines="Both" CellPadding="4" CellSpacing="0"
      OnRowDataBound="GriViewDiv_RowDataBound">
     <HeaderStyle BackColor="#006699" Font-Bold="true" ForeColor="White" />
     <Columns>
     <asp:BoundField DataField="DivID" HeaderText="軟體研發處編號" InsertVisible="false" ReadOnly="true" SortExpression="DivID" />
     <asp:BoundField DataField="DivName" HeaderText="軟體研發處名稱" SortExpression="DivName" />
        <asp:TemplateField HeaderText="軟體研發部信息">
        <ItemTemplate>
        <asp:GridView ID="GridViewDept" runat="server" AutoGenerateColumns="false" DataKeyNames="DeptID" DataSourceID="AccessDataSourceDept" AllowPaging="true" PageSize="2" GridLines="Both" CellPadding="4" CellSpacing="0"
         OnRowDataBound="GridViewDept_RowDataBound">
            <HeaderStyle BackColor="#006699" Font-Bold="true" ForeColor="White" />
            <Columns>
                <asp:BoundField DataField="DeptID" HeaderText="軟體研發部編號" InsertVisible="false" ReadOnly="true" SortExpression="DeptID" />
                <asp:BoundField DataField="DeptName" HeaderText="軟體發部名稱" SortExpression="DeptName" />
                <asp:TemplateField HeaderText="軟體研發課信息">
                    <ItemTemplate>
                        <asp:GridView ID="GridViewSec" runat="server" AutoGenerateColumns="false" DataKeyNames="SecID" DataSourceID="Sec" AllowPaging="true" PageSize="3" GridLines="Both" CellPadding="4" CellSpacing="0">
                            <HeaderStyle BackColor="#006699" Font-Bold="true" ForeColor="White" /> 
                            <Columns>
                                <asp:BoundField DataField="SecID" HeaderText="軟體研發課編號" InsertVisible="false" ReadOnly="true" SortExpression="SecID" />
                                <asp:BoundField DataField="SecName" HeaderText="軟體研發課名稱" SortExpression="SecName" />
                            </Columns>
                            <PagerSettings FirstPageText="首頁" LastPageText="末頁" Mode="NextPreviousFirstLast" NextPageText="下一頁" PreviousPageText="上一頁" />
                        </asp:GridView>
                        <asp:AccessDataSource ID="Sec" runat="server" DataFile="~/SW.mdb" SelectCommand="SELECT [SecID],[SecName] FROM [tb_Sec] WHERE [DeptID]=? ">
                            <SelectParameters>
                                <asp:Parameter Name="DeptID" Type="String"/>
                            </SelectParameters>
                        </asp:AccessDataSource>
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
            <PagerSettings FirstPageText="首頁" LastPageText="末頁" Mode="NextPreviousFirstLast" NextPageText="下一頁" PreviousPageText="上一頁" />
        </asp:GridView>
        <asp:AccessDataSource ID="AccessDataSourceDept" runat="server" DataFile="~/SW.mdb" SelectCommand="SELECT [DeptID],[DeptName] FROM [tb_Dept] WHERE [DivID]=?">
            <SelectParameters>
                <asp:Parameter Name="DivID" Type="String"/>
            </SelectParameters>
        </asp:AccessDataSource>
        </ItemTemplate>
        </asp:TemplateField>
     </Columns>
     <PagerSettings FirstPageText="首頁" LastPageText="末頁" Mode="NextPreviousFirstLast" NextPageText="下一頁" PreviousPageText="上一頁" />
     </asp:GridView>
     <asp:AccessDataSource ID="AccessDataSourceDiv" runat="server" DataFile="~/SW.mdb" SelectCommand="SELECT [DivID],[DivName] FROM [tb_Div]"></asp:AccessDataSource>
    </div>
    </form>

请问在cs页面如何写代码给[DeptID]传递数据得到[软体研发部编号]为1？

补充：.NET技术 ,  C#