Little trouble with MySQL LEFT JOIN I ask your help on a subject that I do not really master.

I have two tables:
tb_user (NIC_Handle, Pseudo)
tb_user_messages_recap (Auteur, Intervenant)

I have to retrieve the NIC_Handle of each 'Pseudo' that corresponds to either 'Auteur' or 'Intervenant'

Can you help me please ?

&lt;?php try{
$MyPDO=$pdo-&gt;query("
SELECT 
tb_user_messages_recap.Auteur,
tb_user_messages_recap.Intervenant,
tb_user_messages_recap.Numero,
tb_user_messages_recap.Sujet,
tb_user_messages_recap.Creation,
tb_user_messages_recap.Edition,
tb_user_messages_recap.Etat,
tb_user.NIC_Handle,
tb_user.Pseudo

FROM tb_user_messages_recap

LEFT JOIN tb_user

ON tb_user_messages_recap.Auteur = tb_user.Pseudo

WHERE tb_user_messages_recap.Auteur='".$_SESSION_PSEUDO."' OR 
      tb_user_messages_recap.Intervenant='".$_SESSION_PSEUDO."' 

ORDER BY Edition DESC
");
    while($data=$MyPDO-&gt;fetch(PDO::FETCH_ASSOC))
    {
?&gt;

&lt;?php echo $data["NIC_Handle"]." - ".$data["Auteur"]; ?&gt;
&lt;?php echo $data["NIC_Handle"]." - ".$data["Intervenant"]; ?&gt;
&lt;?php echo $data["NIC_Handle"]." - ".$data["Intervenant"]; ?&gt;

&lt;?php }}catch(PDOException $e){echo "&lt;div class='alert alert-danger'&gt;".$e-&gt;getMessage()."&lt;/div&gt;";} ?&gt;


Thank you for your help,

Cordialy
Change the join condition to:

ON tb_user_messages_recap.Auteur = tb_user.Pseudo OR
   tb_user_messages_recap.Intervenant= tb_user.Pseudo


But really why not:

SELECT NIC_Handle
FROM tb_user
WHERE Pseudo =$_SESSION_PSEUDO


I could be wrong. Question is a bit ambiguous.