อยากทราบ การเลื่อนลำดับข้อมูลใน db codeigniter (ci)

 <?php
$mn_select = "select * from cmb_menu ORDER BY mn_order ASC";
$result = mysql_query($mn_select);
$num_rows = mysql_num_rows($result);

$prev_mn_id;	 $prev_mn_order;	
$next_mn_id; $next_mn_order;
$row_number = 0;
for(;$row_number<$num_rows; $row_number++){										
$prev_mn_id = 0;
$next_mn_id = 0;
if (@mysql_data_seek ($result , $row_number-1)) {
$prev_list = mysql_fetch_assoc($result);
$prev_mn_id = $prev_list["mn_id"];  // ID
$prev_mn_order = $prev_list["mn_order"];  // order
}
if (@mysql_data_seek ($result , $row_number+1)) {
$next_list = mysql_fetch_assoc($result);
$next_mn_id = $next_list["mn_id"];  // ID
$next_mn_order = $next_list["mn_order"]; // order
}
if (@mysql_data_seek ($result , $row_number)) {
$list = mysql_fetch_assoc($result);
}
?>