if (isset($_COOKIES["session"])) {
   $hash = $_COOKIES["session"];
   $res = mysql_query("SELECT `data` FROM `session` WHERE `hash`='$hash'")
   $data = mysql_fetch_row($res);
   $sdata = $data[0];
   $mysession = unserialize($sdata);
   $mysession["dirty"] = 0;
   $mysession["id"] = $hash;
}

if (isset($mysession) && $mysession["dirty"] == 1) {
   $hash = $mysession["hash"];
   unset($mysession["hash"]);
   unset($mysession["dirty"]);
   $sdata=serialize($mysession);
   mysql_query("REPLACE `session` (`hash`,`data`,`expires`)VALUES('$hash','$sdata',NOW() + INTERVAL 1 HOUR)");
}