如何使用加入从选择更新

How to update from select with a Join(如何使用加入从选择更新)

问题描述

如何更新也存在于子查询中的表?我必须分两个阶段完成吗?(创建一个临时表——将选中的数据放入其中，然后更新最终表)

How can I update a table that is also present in a subquery? Do I have to do it in 2 stages? (create a temporary table - put the selected data in it and then update the final table)

我正在尝试使用每个 CTN 的网络标签更新 invoiceLine 表.

I am trying to update the invoiceLine table with the label of the network for each CTN.

最终结果是:

• 发票行

ctn       network
1234      network1
2345      network2
3456      network1

我有以下表格:

• 发票行

ctn       network
1234      null
2345      null
3456      null

ctn       network
1234      1
2345      2
3456      1

id        label
1         network1
2         network2

我可以运行一个选择，但我不知道如何通过加入进行更新:

I can run a select but I'm not sure how to update with a join:

update invoiceLine 
inner join terminal on terminal.ctn = invoiceLine.ctn 
set invoiceLine.network = 
(
  select network.label 
  from invoiceLine 
  inner join terminal on terminal.ctn = invoiceLine.ctn 
  inner join network on network.id = terminal.network
) 
where invoiceLine.ctn = terminal.ctn

但是 MySQL 抛出一个

but MySQL throws a

错误代码:1093.您不能在 FROM 子句中指定要更新的目标表invoiceLine"

Error Code: 1093. You can't specify target table 'invoiceLine' for update in FROM clause

推荐答案

UPDATE invoiceLine
    INNER JOIN terminal
        ON invoiceLine.ctn = terminal.ctn
    INNER JOIN network
        ON terminal.network = network.id
    SET invoiceLine.network = network.label

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