ca te donnais quoi ca dans ton phpmyadmin ?et comme ca
SELECT *, COUNT(forum_reponses.id) AS num_reponses FROM forum_sujets LEFT JOIN forum_reponses ON forum_reponses.correspondance_sujet = forum_sujets.id
SELECT *, COUNT(forum_reponses.id) AS num_reponses
FROM forum_sujets
LEFT JOIN forum_reponses ON forum_reponses.correspondance_sujet = forum_sujets.id
GROUP BY forum_reponses.correspondance_sujet
dis moi si ca marche la // on affiche le nombre de réponse de ce sujet
$sqlrep = 'SELECT *, COUNT(forum_reponses.id) AS num_reponses FROM forum_sujets LEFT JOIN forum_reponses ON forum_reponses.correspondance_sujet = forum_sujets.id GROUP BY forum_sujets.id ';
$reqrep = mysql_query($sqlrep) or die('<u>Probleme SQL</u> : '.$sqlrep.'<br>'.mysql_error());
while($resultnum = mysql_fetch_array($reqrep))
{
$num_reponses = $resultnum['num_reponses'];
if ($num_reponses == 1)
{
echo '0 réponse';
}
elseif ($num_reponses == 2)
{
echo '1 réponse';
}
else
{
$num_reponses = $num_reponses - 1;
echo $num_reponses.' réponses';
}
}

$req = mysql_query("SELECT forum_sujets.id, forum_sujets.auteur, forum_sujets.titre, forum_sujets.date_derniere_reponse, forum_sujets.vue, forum_reponses.message, forum_reponses.auteur, forum_reponses.correspondance_sujet, COUNT(forum_reponses.id) AS num_reponses FROM forum_sujets INNER JOIN forum_reponses ON (forum_reponses.correspondance_sujet = forum_sujets.id) group by forum_sujets.id order by forum_sujets.date_derniere_reponse desc,forum_reponses.date_reponse desc");