SQL从另一个表中的另一列更新一列

I read various post's prior to this. but none of them seemed to work for me.

我在此之前阅读了各种帖子。但它们似乎都不适合我。

As the title suggests, I am trying to update one column from a column in another table. I don't recall having problems with this before..

正如标题所示，我正在尝试从另一个表中的列更新一列。我不记得以前有这个问题..

1. Table: user_settings.contact_id, I want to update with contacts.id where (user_settings.account_id == contacts_account_id)

1.表：user_settings.contact_id，我想用contacts.id更新where（user_settings.account_id == contacts_account_id）

2. Previously Contacts were linked to user accounts via the account_id. However, now we want to link a contact to user_settings via contacts.id

2.以前通过account_id将联系人链接到用户帐户。但是，现在我们要通过contacts.id将联系人链接到user_settings

Below are a few examples of what I have tried, though none of them have worked. I would be interested in A.) Why they don't work and B.) What should I do instead.

以下是我尝试过的一些例子，尽管它们都没有奏效。我会感兴趣的是A.）为什么他们不工作和B.）我该怎么办呢。

Example A:

例A：

UPDATE user_settings
SET user_settings.contact_id = contacts.id 
FROM user_settings 
INNER JOIN contacts ON user_settings.account_id = contacts.account_id

Example B:

例B：

UPDATE (SELECT A.contact_id id1, B.id id2
  FROM user_settings A, contacts B
  WHERE user_settings.account_id = contacts.account_id)
SET id1 = id2

Example C:

例C：

UPDATE user_settings
SET user_settings.contact_id = (SELECT id
  FROM contacts
  WHERE (user_settings.account_id = contacts.account_id)
WHERE EXISTS ( user_settings.account_id = contacts.account_id )

I feel like my brain just shutdown on me and would appreciate any bumps to reboot it. Thanks :)

我觉得我的大脑只是关闭我，并会感激任何颠簸重新启动它。谢谢：）

2 个解决方案

#1

According to MySQL documentation, to do a cross table update, you can't use a join (like in other databases), but instead use a where clause:

根据MySQL文档，要进行跨表更新，您不能使用连接（就像在其他数据库中一样），而是使用where子句：

http://dev.mysql.com/doc/refman/5.0/en/update.html

I think something like this should work:

我认为这样的事情应该有效：

UPDATE User_Settings, Contacts
    SET User_Settings.Contact_ID = Contacts.ID
    WHERE User_Settings.Account_ID = Contacts.Account_ID

#2

Update tabelName Set SanctionLoad=SanctionLoad Where ConnectionId=ConnectionID
go
update tabelName  Set meterreading=meterreading where connectionid=connectionid
go
update tabelName  set customername=setcustomername where customerid=customerid

#1