甲骨文

use

UPDATE suppliers
SET supplier_name = (SELECT customers.customer_name
                     FROM customers
                     WHERE customers.customer_id = suppliers.supplier_id)
WHERE EXISTS (SELECT customers.customer_name
              FROM customers
              WHERE customers.customer_id = suppliers.supplier_id);

MYSQL(这是我最喜欢的恢复所有特定列reasonId值的方法，基于主键id等价)

UPDATE `site` AS destination  
INNER JOIN `site_copy` AS backupOnTuesday 
      ON backupOnTuesday.`id` = destination.`id`
SET destdestination.`reasonId` = backupOnTuesday.`reasonId`

对于MySql工作良好:

UPDATE
    Sales_Import SI,RetrieveAccountNumber RAN
SET
    SI.AccountNumber = RAN.AccountNumber
WHERE
    SI.LeadID = RAN.LeadID

我对foo也有同样的问题。对于在bar中没有匹配键的foo行，New被设置为null。我在Oracle做了类似的事情:

update foo
set    foo.new = (select bar.new
                  from bar 
                  where foo.key = bar.key)
where exists (select 1
              from bar
              where foo.key = bar.key)

总结其他答案，关于如何仅在“匹配存在”时使用来自另一个表的数据更新目标表，有4种变体

查询和子查询:

update si
set    si.AccountNumber = (
    select ran.AccountNumber 
    from   RetrieveAccountNumber ran
    where  si.LeadID = ran.LeadID
)
from Sales_Import si
where exists (select * from RetrieveAccountNumber ran where ran.LeadID = si.LeadID)

内连接:

update si
set si.AccountNumber = ran.AccountNumber
from Sales_Import si inner join RetrieveAccountNumber ran on si.LeadID = ran.LeadID

交叉连接:

update si
set si.AccountNumber = ran.AccountNumber
from Sales_Import si, RetrieveAccountNumber ran
where si.LeadID = ran.LeadID

走：

merge into Sales_Import si
using RetrieveAccountNumber ran on si.LeadID = ran.LeadID 
when matched then update set si.accountnumber = ran.accountnumber;

所有的变体都是更少的琐碎和可以理解的，我个人更喜欢“内部连接”选项。但其中任何一种都可以使用，开发者必须根据自己的需求选择“更好的选项”

从性能的角度来看，使用join的变体更可取:

更新表1 DPM set col1 = dpu。Col1 from table2 dpu其中dpm。Parameter_master_id = dpu.parameter_master_id;