problema stupidissimo.. perche', con questo codice:

codice:
$query = "SELECT * FROM `aperture` WHERE  `username` = '" .$_POST['usern']. "' ";
    echo $query; 			 
while($result = mysql_fetch_assoc($query))
 	{
	 echo $result;	
	}
mi da' questo errore????

codice:
Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in c:\inetpub\wwwroot\nmcweb\conferma.php on line 93