function languageExists($login, $language)
{
    $id = languetoid($language);
    $dbh = Database::connect();
    $query = "SELECT * FROM `known_languages` WHERE `login`='{$login}' AND `language_id`='{$id}' ";
    $sth = $dbh->prepare($query);
    $sth->execute();
    $aux = $sth->fetch(PDO::FETCH_ASSOC);
    $dbh = null;
    if ($aux == NULL) {
        return FALSE;
    } else {
        return TRUE;
    }
}
function rateRequest($login1, $login2, $ratedlevel, $language)
{
    $id = languetoid($language);
    $dbh = Database::connect();
    $sth = $dbh->prepare("SELECT * FROM `rating_requests` WHERE  `login1`='{$login1}' AND `login2`='{$login2}' AND `language_id`='{$id}'");
    $sth->execute();
    if ($sth->fetch(PDO::FETCH_ASSOC)) {
        echo "You have already rated {$login2}'s {$language} ability, your score for {$login2} will be updated! <br>";
        $sth = $dbh->prepare("DELETE FROM `rating_requests` WHERE (`login1`, `login2`,`language_id`)=(?,?,?)");
        $sth->execute(array($login1, $login2, $id));
    }
    // TO ADD : WHAT HAPPENS IF SAME USER TRIES TO RATE USER2 FOR SAME LANGUAGE : UPDATES
    $sth = $dbh->prepare("INSERT INTO `rating_requests` (`login1`, `login2`,`language_id`,`ratedlevel`) VALUES(?,?,?,?)");
    $sth->execute(array($login1, $login2, $id, $ratedlevel));
    $dbh = null;
    // Déconnexion de MySQL
    //login1 is the rater, login2 is rated
}