具有内部联接的Oracle Update语句 [英] Oracle Update statement with an Inner Join

问题描述

我正在尝试使用内部联接编写一个简单的更新语句，但是我在SQL Server中执行此操作的方式似乎在ORACLE中不起作用.这是更新:

I am trying to write a simple update statement with an inner join, but the way I would do this in SQL server does not seem to be working in ORACLE. Here is the Update:

UPDATE D
SET D.USER_ID = C.USER_ID
FROM D INNER JOIN C 
ON D.MGR_CD = C.MGR_CD WHERE D.USER_ID IS NULL;

似乎我得到的错误是在FROM上.有人可以解释一下这是什么原因以及如何解决它吗?

It seems like the error I am getting is on the FROM. Can someone explain to meet what the cause of this is and how to work around it?

推荐答案

在Oracle中，您不能在

In Oracle, you can't use a from clause in an update statement that way. Any of the following should work.

UPDATE d
SET    d.user_id   =
          (SELECT c.user_id
           FROM   c
           WHERE  d.mgr_cd = c.mgr_cd)
WHERE  d.user_id IS NULL;

UPDATE (SELECT d.user_id AS d_user_id, c.user_id AS c_user_id
        FROM   d INNER JOIN c ON d.mgr_cd = c.mgr_cd
        WHERE  d.user_id IS NULL)
SET    d_user_id   = c_user_id;

UPDATE (SELECT d.user_id AS d_user_id, c.user_id AS c_user_id
        FROM   d INNER JOIN c ON d.mgr_cd = c.mgr_cd)
SET    d_user_id   = c_user_id
WHERE  d_user_id IS NULL;

但是，我更喜欢在这种情况下使用MERGE:

However, my preference is to use MERGE in this scenario:

MERGE INTO d
USING      c
ON         (d.mgr_cd = c.mgr_cd)
WHEN MATCHED THEN
    UPDATE SET d.user_id = c.user_id
        WHERE      d.user_id IS NULL;

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