<?php
$query = "SELECT CONCAT_WS('/',f1,f2) AS f1,f3,f4,f5 FROM mw ORDER BY f3 ASC";
$res = mysql_query($query) or die(mysql_error());
$arr = array();
while($row = mysql_fetch_assoc($res)){
$arr[] = $row;
}
//print_r($arr);
$group = $arr[0]['f3'];
echo '<b>' .$group. '</b><hr>';
foreach($arr as $item){

if($group != $item['f3']){
  echo '<b>' .$item['f3']. '</b><hr>';
  $group = $item['f3'];
}

echo $item['f1']. ' || ';
echo $item['f3']. ' || ';
echo $item['f4']. ' || ';
echo $item['f5']. '<br>';
}
?>