$subQuery = $db->buildStatement(
        array(
                'fields'     => array('"ParentNode"."id"', '"ParentNode"."type"'),
                'table'      => $db->fullTableName($this->Node),
                'alias'      => 'ParentNode',
                'limit'      => null,
                'offset'     => null,
                'joins'      => array(),
                'conditions' => $conditionsSubQuery,
                'order'      => null,
                'group'      => null
        ),
        $this->Node
);