static public function retrieveTree(Criteria $criteria = null, ConnectionInterface $con = null)
    {
        if (null === $criteria) {
            $criteria = new Criteria(CategoryTableMap::DATABASE_NAME);
        }
        $criteria->addAscendingOrderByColumn(ChildCategory::LEFT_COL);

        return ChildCategoryQuery::create(null, $criteria)->find($con);
    }