Aggiornare tabella da array

[Protooler]

Sto provando in questo modo ma senza risultato..

$cg = $_POST['cg']; //id della news
if ($rel <> ""):
    $query = "SELECT * FROM relation WHERE idn='$cg' AND idb='$brandrel'";
    $res = mysql_query($query);
    foreach($rel as $brandrel){
        while ($row = mysql_fetch_array($res)) :
            echo $row[idb];
            if ($brandrel == $row[idb]) {
                $upd1=mysql_query("UPDATE relation SET idb = \"$brandrel\" WHERE idn = \"$cg\"");
            }    
            else {
                $ins1=mysql_query("INSERT INTO relation(idn, idb) VALUES('$cg', '$brandrel')");
            }
        endwhile;
    }
endif;