aspx文件中加
<script language="javascript">
  <!--
  //checkbox全選and反全選
  function select_deselectall (chkval, idval)
  {
   var frm = document.forms[0];
   for (i=0; i<frm.length; i++)
   {
    if (idval.indexof ('checkall') != -1)
    {
     if(chkval == true)
     {
      frm.elements[i].checked = true;
     }
     else
     {
      frm.elements[i].checked = false;
     }
    }
    else if (idval.indexof('deletethis') != -1)
    {
     if(frm.elements[i].checked == false)
     {
      frm.elements[1].checked = false;
     }
    }
   }
         }
   //-->
</script>

全選<input id="checkall" tabindex="0" type="checkbox" title="點擊全選或反全選當前頁所有信息">

datagrid中加模板列
<asp:templatecolumn headertext="選定">
<headerstyle width="10%"></headerstyle>
<itemtemplate>
<asp:checkbox id="chkselectbox" runat="server"></asp:checkbox>
</itemtemplate>
</asp:templatecolumn>

cs文件中操作選定項
foreach (datagriditem item in datagrid.items)
{
 if(((checkbox)item.findcontrol("chkselectbox")).checked==true)
 { 
  response.write (item.cells[0].text);
 }
}