questions about the datagrid

[smith.felicity]

I have two questions about using the data grid and c#

If one of my columns returned in my dataset is null I want another
column to be used in the displayed column.

So this is what my datagrid looks like
<asp:datagrid id="datagrid1" runat="Server" allowpaging="true"
pagesize="25" autogeneratecolumns="False">
<asp:hyperlinkcolumn datanavigateUrlField="col3"
dataNavigateUrlFormatString="{0}" dataTextField="col1"

</<asp:hyperlinkcolumn>

<asp:boundcolumn headerText="col2" DataField="col2"></<asp:boundcolumn>
</asp:datagrid>
basically I want to detect if the value of col1 is null and if so, to
use the value of col2 here.
My second question is how do I do row numbering in my data grid so my
columns look like this

RowNumber Col1 Col2 Col3
1 col1data col2data col3data

TIA

Felicity