echo $data['montant'];
voici mon code (<?php $sql2 = 'SELECT SUM(montant) FROM versements WHERE n_doss=' . $_GET['n_doss'] . '';
$req2 = mysql_query ($sql2) or die ('Erreur SQL !<br>'.$sql2.'<br>'.mysql_error ());
while($data = mysql_fetch_assoc ($req2))
{
echo $data['montant'];
} ?>
D'avance merci.