MySQL 依赖另外一个统计出来数据更新表数据的范例

MySQL 依赖另外一个统计出来数据更新表数据的范例：
update goods g,(SELECT goods_id ,sum(product_number) as num
FROM `products`
group by goods_id) b
set goods_number = num
where g.goods_id = b.goods_id