mysql - mysql INNER JOIN 与 WHERE。需要了解代码的作用

Question

桌子2_1_journal

TransactionPartnerName 
-----------------------
 name 1
 name 2
 name 3

桌子2_1_transactionpartners

CompanyName   |  PreviousCompanyName
------------------------------------
 name 1       |   
 name 2       |   
 name 3       |  name 2

name 1比如想改成name 11.

首先在表格中复制2_1_transactionpartners并粘贴name 1CompanyNamePreviousCompanyName

接下来需要在表中2_1_journal更改name 1为name 11。我认为：更改TransactionPartnerName为CompanyNamewhereTransactionPartnerName等于PreviousCompanyName。但我不想在表中2_1_journal更改name 2为，name 3因为只想（给出命令）更改name 1为name 11.

这是我的代码。没有发现错误。但是想确定代码的作用

UPDATE 2_1_journal 
INNER JOIN 2_1_transactionpartners ON (2_1_journal.TransactionPartnerName = 2_1_transactionpartners.PreviousCompanyName)
SET 2_1_journal.TransactionPartnerName = 2_1_transactionpartners.CompanyName
WHERE 2_1_transactionpartners.CompanyName = ?

?=name 11

理解代码更新2_1_journal并复制CompanyName到TransactionPartnerNameifCompanyName等于name 11和TransactionPartnerName等于PreviousCompanyName

我对么？可能有更好的方法来达到目标​​吗？

Answer 1

UPDATE IGNORE 2_1_transactionpartners, 2_1_journal 
SET 2_1_journal.TransactionPartnerName = 2_1_transactionpartners.CompanyName
WHERE 2_1_journal.TransactionPartnerName =  
2_1_transactionpartners.PreviousCompanyName
AND 2_1_transactionpartners.CompanyName = ?