You can easily pass multiple fields in the querystring when using the GridView HyperLinkField column. Take a look at the code below:
<asp:GridView ID="gvCategories" runat="server" >
<Columns>
<asp:HyperLinkField DataTextField="CategoryName" DataNavigateUrlFields="CategoryID,CategoryName,Description" DataNavigateUrlFormatString="~/Learning.aspx?categoryID={0}&categoryName={1}&description={2}" />
</Columns>
</asp:GridView>
Easy is'nt it!