public function create()
    {
        if ($this->createStatement == null) {
            $this->createStatement = $this->connection->prepare("
            INSERT INTO User (username,mail,password,id,parent) VALUES (?,?,?,?,?)");
            $this->createStatement->bindParam(1, $this->username);
            $this->createStatement->bindParam(2, $this->mail);
            $this->createStatement->bindParam(3, $this->password);
            $this->createStatement->bindParam(4, $this->userId);
            $this->createStatement->bindParam(5, $this->parentID);
        }
        try {
            $this->createStatement->execute();
        } catch (PDOException $e) {
            return false;
        }
        $this->setInitialValues();
        return $this->exists();
    }