为什么我的MySQL更新语句涉及2个表不起作用？

Question

我确信可行的更新声明是这样的：

UPDATE products SET manufacturers_id = 37 where products_id = 
(select products_id from     products_to_categories where categories_id = 35);

但是在PHPMyAdmin中，我得到的错误是：

#1242 - Subquery returns more than 1 row

但我希望更新1行以上。我试图在一个声明中更新100或更多。如何重写这样才能起作用？我必须使用加入吗？

Answer 1

您应该使用IN而不是=

UPDATE
  products
SET
  manufacturers_id = 37
WHERE
  products_id IN (SELECT products_id
                  FROM products_to_categories 
                  WHERE categories_id = 35);

或者您可以使用JOIN

UPDATE
  products INNER JOIN products_to_categories 
  ON products.product_d = products_to_categories.products_id
SET
  products.manufacturers_id = 37
WHERE
  products_to_categories.categories_id = 35

Answer 2

试试这个

 UPDATE products SET manufacturers_id = 37 where products_id in 
 (select products_id from     products_to_categories where categories_id = 35);

将=更改为IN