mysql update sum 1 code example

Example 1: mysql update set sum

UPDATE products p,( SELECT products_id, sum(attributes_stock)  as mysum
                   FROM products_attributes GROUP BY products_id) as s

   SET p.products_quantity = s.mysum
  WHERE p.products_id = s.products_id

Example 2: mysql update sum same table

UPDATE products SET quantity = quantity + 10 WHERE id = 8