更新MySql表相关的记录关系而不会丢失数据

Question

我有三个MySql表

类别表：

id        link_id     category_id
--------------------------------------
1          5           10
2          6           12
3          5           12

链接表：

link_id    link_title         link_url        website_id
-------------------------------------------------------
5          title            test.com/test         1
6          title2           test.com/test2        1
7          title3           link.com/linklist     2

网站表：

website_id      url
-----------------------------
1               test.com
2               link.com

现在我需要将类别表link_id更改为website_id 像这样

id        link_id(/website_id)     category_id
--------------------------------------
1          1                    10
2          2                    12
3          1                    12

这是否可以使用MySql更新查询

提前谢谢！

Answer 1

你可以加入两个表，

UPDATE  category a
        INNER JOIN link b
            ON a.link_id = b.link_ID
SET     a.link_ID = b.website_ID

• SQLFiddle Demo

Answer 2

尝试此查询，但请确保在执行此操作之前进行备份。

UPDATE category AS c
  INNER JOIN Link AS l
    ON l.link_id = c.link_id
SET c.link_id = l.website_id

Answer 3

UPDATE category
SET link_id = website_id FROM Link L
WHERE L.link_id = category.link_id

Answer 4

你能试试吗??

update catagory a
set a.link_id = (
  select b.website_id from link b
  inner join website c on b.website_id = c.website_id
    where a.link_id= b.link_id)