$sql = $db->query("SELECT user_shortlink FROM ".$prefix."users WHERE user_shortlink=\"".escapestr($_POST["shortlink"])."\" and user_id <> \"".$authinfo["user_id"]."\";");
if ($db->rows($sql) == 1)
{
    $error = 1;
    $message .= "Адрес занят!<br/>";
}
$db->freeresult($sql);


// Пример с unset

$tpl = new File();
$tpls = $tpl->makefilelist(TEMPLATES, ".|..", true, "", "folders");
echo $tpl->makefileopts($tpls, $authinfo["user_template"]);
unset($tpl);
unset($authinfo);