In the GridView, the BoundField is changed to a TemplateField and populated like this:
<asp:TemplateField HeaderText="Priority" SortExpression="some_select_field">
<EditItemTemplate>
</EditItemTemplate>
<asp:DropDownList ID="DropDownList1" runat="server" SelectedValue='<%# Bind("some_select_field") %>'>
</asp:DropDownList>
<asp:ListItem Value="H">H</asp:ListItem>
<asp:ListItem Value="M">M</asp:ListItem>
<asp:ListItem Value="L">L</asp:ListItem>
<asp:ListItem Value="">Not Set</asp:ListItem>
<asp:ListItem Value="M">M</asp:ListItem>
<asp:ListItem Value="L">L</asp:ListItem>
<asp:ListItem Value="">Not Set</asp:ListItem>
</asp:DropDownList>
</EditItemTemplate>
<ItemTemplate>
</ItemTemplate>
<asp:Label ID="Label1" runat="server" Text='<%# Bind("some_select_field") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
'some_select_field' is just some field returned by the SQLDataSource's SelectCommand:
<asp:SqlDataSource ID="SqlDataSource1" runat="server"ConnectionString="<%$ ConnectionStrings:FAA_ConnectionString %>"
ProviderName="<%$ ConnectionStrings:FAA_ConnectionString.ProviderName %>" SelectCommand="Select some_select_field from some_sql_table">
</asp:SqlDataSource>
Dave