Howto use multiple QueryStringParameters in a SelectCommand for a MySQL SqlDataSource

I am trying to use multiple QueryStringParameters in a SelectCommand for a MySQL SqlDataSource. I can use 1 just fine like this:

[CODE]
<asp:SqlDataSource ID="db_faa" runat="server"
                ConnectionString="Dsn=my_faa;uid=root;pwd=root"
                ProviderName="System.Data.Odbc"
                SelectCommand="SELECT faa_part, faa_part_desc, faa_status FROM tbl_faa_tracking WHERE faa_pl_desc = ?">
                <SelectParameters>
                       <asp:QueryStringParameter Name="value" QueryStringField="value" />
                </SelectParameters>
            </asp:SqlDataSource>
[/CODE]

and a query string like this:  ?value=TE456

But I actually need to pass in the field name as well like this:  ?field=faa_pl_desc&value=TE456
so I tried changing the code to this:

[CODE]
<asp:SqlDataSource ID="db_faa" runat="server"
                ConnectionString="Dsn=my_faa;uid=root;pwd=root"
                ProviderName="System.Data.Odbc"
                SelectCommand="SELECT faa_part, faa_part_desc, faa_status FROM tbl_faa_tracking WHERE ? = ?">
                <SelectParameters>
                    <asp:QueryStringParameter Name="field" QueryStringField="field" />
                    <asp:QueryStringParameter Name="value" QueryStringField="value" />
                </SelectParameters>
            </asp:SqlDataSource>
[/CODE]

I get no error, I just get a blank data set. It is as if the Select is returning no data even tho it has the same field name and search value in both instances. I have tired reversing the order of the 2 QueryStringParameters just in case the parameters are in a stack instead of a FIFO. No joy...

I think I just must be passing the 2 Query strings with some syntax missing?

Dave