function user_is_in_group($groupname) {
    global $db,$user_data;
    if (empty($groupname)) return false;
    $request = "select group_id from ".TABLE_GROUP." where group_name like '".mysql_real_escape_string($groupname)."' limit 1";
    $result = $db->sql_query($request);
    if ( list($group_id) = $db->sql_fetch_row($result) ) {
        $request="SELECT count(*)"
            ." FROM ".TABLE_USER_GROUP
            ." WHERE user_id='".intval($user_data["user_id"])."' AND group_id='".$group_id."'";
			
        $result = $db->sql_query($request);
        list($isingroup) = $db->sql_fetch_row($result);
        if ($isingroup=1) return true;
    }
    return false;
}