Aide requete SQL

while($row = mysql_fetch_array($req10))
{
	$user=$row['username'];
}

while($row = mysql_fetch_array($req10))
{
	$users[]=$row['username'];
}

foreach ($users as $user)
{
          /* A cache occurence dans cette boucle, $user sera la variable
          qui représente une des cases du tableau $users */
}

<?
	include("connexion.php");
	$sql10="SELECT * FROM phpbb_users ORDER BY 'user_id' desc limit 10 ";
	$req10 = mysql_query($sql10) or die('Erreur SQL !<br>'.$sql10.'<br>'.mysql_error());
	$row = mysql_fetch_array($req10);
	while($row = mysql_fetch_array($req10))
	{
	$users[]=$row['username'];
	}
	foreach ($users as $user)
		{
		echo $user;
		}
	?>

<?
	include("connexion.php");
	$sql10="SELECT * FROM phpbb_users ORDER BY 'user_id' desc limit 10 ";
	$req10 = mysql_query($sql10) or die('Erreur SQL !<br>'.$sql10.'<br>'.mysql_error());
	$i =0;
	while($row =mysql_fetch_assoc($req10))
	{
	         $users[$i]=$row['username'];
                 $i++;
	}
	foreach ($users as $user)
		{
		echo $user;
		}
	?>

        foreach ($users as $user)
	{
		echo $user."<br>";
	}

        while($row =mysql_fetch_assoc($req10))
	{
	         $users[$i]=$row['username'];
                 echo $row['username']."<br>";
                 $i++;
	}