function lfRenumber($parent_category_id) {
        $objQuery =& SC_Query_Ex::getSingletonInstance();
        $query ='
            CREATE TEMPORARY TABLE dtb_product_categories2 (
                product_id int NOT NULL,
                category_id int NOT NULL,
                rank int NOT NULL,
                PRIMARY KEY(product_id, category_id)
            );
        ';
        $objQuery->query($query);
        
        $query = '
        INSERT INTO dtb_product_categories2
        SELECT
            *
        FROM    
            dtb_product_categories
        ';
        $objQuery->query($query);
        $sql = <<< __EOS__
            UPDATE dtb_product_categories
            SET
                rank =
                    (
                        SELECT COUNT(*) as cnt
                        FROM dtb_product_categories2 t_in
                        WHERE t_in.category_id = dtb_product_categories.category_id
                            AND (
                                t_in.rank < dtb_product_categories.rank
                                OR (
                                    t_in.rank = dtb_product_categories.rank
                                    AND t_in.product_id < dtb_product_categories.product_id
                                )
                            )
                    ) + 1
            WHERE dtb_product_categories.category_id = ?
__EOS__;
        $arrRet = $objQuery->query($sql, array($parent_category_id));
        return $arrRet;
    }