$tmp = $db->query("SELECT DISTINCT idl FROM mesages WHERE ida='".$getuser['id']."' ORDER BY date DESC
                UNION SELECT DISTINCT idl FROM achuvedoms WHERE ida='".$getuser['id']."' ORDER BY date DESC");

$tmp = $db->query("SELECT * FROM (
                SELECT DISTINCT idl FROM mesages WHERE ida='".$getuser['id']."'
                UNION SELECT DISTINCT idl FROM achuvedoms WHERE ida='".$getuser['id']."'
                ) results ORDER BY date DESC");