插入引用另一个表的值 [英] Insert values referring to another table

问题描述

我创建了以下简单的datamodel:

我使用以下insert statements插入值:

1)表产品:

INSERT INTO test.products
(ProductName, Price)
VALUES 
("Product A","99,99"),
("Product B","49,95"), 
("Product C","5,95");

2)表订单:

INSERT INTO test.orders
(Customer)
VALUES 
("Customer A"),
("Customer B"), 
("Customer B");

到目前为止，所有这些都可以正常工作.

All this works fine so far.

但是，现在我也想在表Products_per_Order中插入值.
如您在datamodel中所见，Products_per_Order表包含列Price.在此列中，我要参考Products_idProducts列中的 ID 插入价格.因此，我尝试使用以下insert statement，但到目前为止无法正常工作:

However, now I also want to insert values into the table Products_per_Order.
As you can see in the datamodel the Products_per_Order table contains the column Price. In this column I want to insert the price referring to the ID in the column Products_idProducts. Therefore, I tried to go with the following insert statement but could not make it work so far:

INSERT INTO test.products_per_order
(Orders_idOrders, Products_idProducts, Price, Quantity)
VALUES
("1","1",(Select Price from test.products),"5"),
("1","2",(Select Price from test.products),"4"),
("2","1",(Select Price from test.products),"10"),
("3","2",(Select Price from test.products),"3"),
("3","3",(Select Price from test.products),"9");

您知道如何解决此问题吗?

Do you have any idea how to solve this issue?

推荐答案

我建议改用insert . . . select:

insert into test.products_per_order (Orders_idOrders, Products_idProducts, Price, Quantity)
    select x.idOrder, x.idProduct, p.price, x.qty
    from (select 1 as idOrder, 2 as idProduct, 5 as qty union all
          select 1 as idOrder, 2 as idProduct, 4 as qty union all
          . . .  -- I've left these out so you can see the structure of the query
          select 3 as idOrder, 3 as idProduct, 9 as qty
         ) x left join
         test.products p
         on p.idProducts = x.idProduct;

这使错字导致错误价格的可能性大大降低.

This makes it much less likely that a typo will result in the wrong price.

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