INSERT OR UPDATE

if(($_GET['co'] =="change") && isset($_POST['change']))
{
    foreach($_POST as $key => $value)
    {
        if($key != "change")
        {
            $query = "INSERT INTO m_api_nastaveni (par, val) VALUES ('$key', '$value') ON DUPLICATE KEY UPDATE par='".$key."',val='".$value."'";
            mysql_query($query) or die(mysql_error());
        }
    }
}