mysql_fetch_array

[Mivio84]

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in c:\programmi\apache group\apache\htdocs\fgf\frame-appno.php on line 10

altro problema, non riesco a capire il perchè.questo è il codice:

<?php 
    session_start();
    
    include ("ConnessioneDB.php");
    
    $User = $_SESSION['User'];

    $sql_query = "SELECT * FROM riparatori WHERE User = '$User'";
    $ris_query = mysql_query($sql_query);
    $Riga = mysql_fetch_array ($ris_query);
    $Lun = $Riga[Lun];
    $Mar = $Riga[Mar];
    $Mer = $Riga[Mer];
    $Gio = $Riga[Gio];
    $Ven = $Riga[Ven];
?>