$('#example').dataTable({
            "bProcessing": true,
            "bServerSide": true,
            "aaSorting": [[2, "asc"]],
            "sAjaxSource": "/userControl/GetUser.php",
            "aoColumnDefs": [{
                "aTargets": [0],
                "mData": "download_link",
                "mRender": function (data, type, full) {
                    return '<a href="/UserDetail.aspx?ID=' + data + '">Detail</a><br/><a href="/UserDetail.aspx?ID=' + data + '">Delete</a>';
                }
            }],
              "aoColumns": [
            { "mData": null },
            { "mData": "LoginId" },
            { "mData": "FirstName" },
            { "mData": "LastName" }
        ]
        });

    var oTable = $('#example').dataTable();

    oTable.fnSort([1, 'asc']);