$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"); 

	// 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';
				}
			}

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

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

ok bon de tout facon sa resoud pas le probleme qui est toujours le même.

	<?php
	// on prépare notre requête
	$sql = 'SELECT auteur, message, date_reponse FROM forum_reponses WHERE correspondance_sujet="'.$_GET['id_sujet_a_lire'].'" ORDER BY date_reponse ASC';
	// on lance la requête (mysql_query) et on impose un message d'erreur si la requête ne se passe pas bien (or die)
	$req = mysql_query($sql);
	//on conte le nombre de reponses:
	$nb_sujets = mysql_num_rows ($req);
	
if ($nb_sujets == 0) 
{
	echo 'Aucun sujet';
}
else {
//on soustrait au nombre total le message d'origine qui n'est pas un réponse
$nb_sujets = $nb_sujets-1;
echo '<h2><span class="orange">Nombre de réponse(s) pour ce sujet : </span><span class="bleu">' .$nb_sujets.'</span></h2>';
}
?>

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'reponses FROM forum_sujets LEFT JOIN forum_reponses ON forum_reponses . corres' at line 1

SELECT *, COUNT(forum_reponses.id) AS num_ reponses
FROM forum_sujets
LEFT JOIN forum_reponses ON forum_reponses.correspondance_sujet = forum_sujets.id