c# - Sorting of Gridview data -

i have grid view , want sort gridview .i tried severel methods google , not working in side.

my gridvie code

<asp:gridview id="gridviewshopdata" runat="server" datasourceid="sqldatasource1" width="100%"                         allowsorting="true"  autogeneratecolumns="false" gridlines="none"                         cssclass="contactlist grid"  pagesize="30" showheaderwhenempty="true">     <columns>         <asp:templatefield headertext="fornavn">             <itemtemplate>                 <%# eval("fornavn") %>             </itemtemplate>         </asp:templatefield>          <asp:templatefield headertext="efternavn">             <itemtemplate>                    <%# eval("efternavn") %>             </itemtemplate>         </asp:templatefield>          <asp:templatefield headertext="medarbejder nummer">             <itemtemplate>                    <%# eval("medarbejder nummer") %>             </itemtemplate>         </asp:templatefield>          <asp:templatefield headertext="varenummer">             <itemtemplate>                    <%# eval("varenummer") %>             </itemtemplate>         </asp:templatefield>     </columns>     <alternatingrowstyle cssclass="altrow" />                         <pagersettings firstpagetext="first" lastpagetext="last" pagebuttoncount="50" />                         <emptydatatemplate>                             there no data available display!                         </emptydatatemplate>     <pagerstyle cssclass="pager" />   </asp:gridview> <asp:sqldatasource id="sqldatasource1" runat="server" selectcommand="select firstname 'fornavn',lastname 'efternavn',employeenumber 'medarbejder nummer',productid 'varenummer' sydshoporder shopid=@pageid">     <selectparameters><asp:querystringparameter name="pageid" querystringfield="id"/></selectparameters>  </asp:sqldatasource> 

how make possible help.

set sortexpression in template field , try

<asp:templatefield headertext="fornavn" sortexpression="fornavn">             <itemtemplate>                 <%# eval("fornavn") %>             </itemtemplate>         </asp:templatefield> 

do columns want sort