Boucles Mysql

Quelques chose comme:

<?php
$n=0;
$sql='SELECT * FROM table1';
$req = mysql_query($sql) or die('Erreur SQL !<br />'.$sql.'<br />'.mysql_error());
while($data = mysql_fetch_array($req))
        {
        $sql2 = 'SELECT * FROM table2 WHERE mail="'.$data['mail'].'"';
        $req2 = mysql_query($sql2) or die('Erreur SQL !<br />'.$sql2.'<br />'.mysql_error());
        $nb2 = mysql_fetch_array($req));
        if($nb2!=0)
                {
                $sql3='DELETE FROM table2 WHERE mail="'.$data['mail'].'"';
                mysql_query($sql3) or die('Erreur SQL !<br />'.$sql3.'<br />'.mysql_error());
                $n++;
                }
        }

echo $n.' mails supprimés';
?>