public function revokeAllPrivileges()
    {
        if ($this->revokeAllStatement == null) {
            $this->revokeAllStatement =
                $this->connection->prepare("DELETE FROM UserPrivileges WHERE username = ?");
            $u = $this->user->getUsername();
            $this->revokeAllStatement->bindParam(1, $u);
        }
        $this->revokeAllStatement->execute();
        $this->rootPrivilege = $this->sitePrivilege = 0;
        $this->pagePrivilege = array();
    }