Rsa97

UPDATE `product` AS `p`
  JOIN (
    SELECT `product_id`, SUM(`quantity`) AS `quantity`
      FROM `product_option`
      WHERE `subtract` = 1 
      GROUP BY `product_id`
  ) AS `o` USING(`product_id`)
  SET `p`.`quantity` = `o`.`quantity`

Ведь как-то больно получается писать название каждой из таблиц, а если 100 таблиц будет?

SET @last = 0;
SELECT `ID_1`, @last := `ID_2` AS `ID_2`
  FROM (
    SELECT `ID_1`, `ID_2` 
      FROM `table`
      ORDER BY `ID_1`, `ID_2`
  ) AS `t`
  WHERE `ID_1` > @last;