Little trouble with MySQL LEFT JOIN

Question

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 ?

<?php try{
$MyPDO=$pdo->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->fetch(PDO::FETCH_ASSOC))
    {
?>

<?php echo $data["NIC_Handle"]." - ".$data["Auteur"]; ?>
<?php echo $data["NIC_Handle"]." - ".$data["Intervenant"]; ?>
<?php echo $data["NIC_Handle"]." - ".$data["Intervenant"]; ?>

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

Thank you for your help,

Cordialy

Answer 1

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.