mysql - mysql，使用选择子查询插入

Question

我的表中有很多产品，product_category其中 acategory_id为 5。我添加了一个新category_id的 19。如何将类别 5 中的所有产品也添加到类别 19？

我正在尝试做这样的事情：

insert into product_categories( category_id, product_id )
select 19,
   (select product_id
    from product_categories
    where category_id = 5)

但我得到一个sub query returns more than 1 row错误。

Answer 1

试试这个：

INSERT INTO product_categories (category_id, product_id)
  SELECT 19 AS category_id, product_id 
  FROM product_categories 
  WHERE category_id =5;

Answer 2

尝试这样的事情：

INSERT INTO product_categories( category_id, product_id )
SELECT 19, product_id FROM product_categories WHERE category_id =5

Answer 3

你可以这样做：

INSERT INTO table_a (field, field, timestamp) 
 VALUES (
     (SELECT id FROM tablex WHERE id = :xid LIMIT 1),
     (SELECT id FROM tabley WHERE id = :yid LIMIT 1),
     NOW()
 )

Answer 4

尝试限制

INSERT INTO product_categories( category_id, product_id ) SELECT 19 , (

SELECT product_id FROM product_categories WHERE category_id =5 LIMIT 1)