public function Update($userid){
        echo $userid;
        $PDO = Db::getInstance();
        if(!empty($this->m_sUsername) && !empty($this->m_sEmail) && !empty($this->m_sPassword) && !empty($this->m_sPasswordconfirmation)){
            if($this->m_sPassword == $this->m_sPasswordconfirmation){
                $options= ['cost' => 12];
                $this->m_sPassword = password_hash($this->m_sPassword, PASSWORD_DEFAULT, $options);

                $stmt = $PDO->prepare("UPDATE users SET username= :username, email = :email, password = :password WHERE usersid = :usersid");
                $stmt->bindValue(":usersid", $userid, PDO::PARAM_STR);
                $stmt->bindValue(":username", $this->m_sUsername, PDO::PARAM_STR);
                $stmt->bindValue(":email", $this->m_sEmail, PDO::PARAM_STR);
                $stmt->bindValue(":password", $this->m_sPassword, PDO::PARAM_STR);
                if($stmt->execute()){
                    // success
                    throw new exception("Je aanpassingen zijn doorgevoerd");
                }else{
                    // error
                    throw new exception("Je hebt ergens een fout ingevuld");
                }
            }else{
                // Mismatch password
                throw new exception("Wachtwoorden komen niet overeen");
            }
        }else{
            // some values are not set
            throw new exception("Je hebt enkele velden niet ingevuld");
        }
    }