SQL：联接两个表（LEFT OUTER JOIN），然后更新值

Question

我试图根据另一张表中的值更新一列中的值。

如果列都在同一表中，则可以执行以下操作：

UPDATE wp_posts 
SET post_date = REPLACE (post_date, 'X', 'Y') 
WHERE meta_value = 'Z';

但是我需要先连接两个表才能进行更新：

SELECT * 
FROM wp_posts 
LEFT OUTER JOIN wp_postmeta ON post_id = post_id

如何根据已加入的两个表进行更新？

Answer 1

如果您使用SQL Server ，请尝试这种方式

UPDATE WP
SET WP.post_date = REPLACE(WPM.post_date, 'X', 'Y') 
FROM wp_posts WP 
   LEFT OUTER JOIN wp_postmeta WPM ON WP.post_id = WPM.post_id
WHERE WP.meta_value = 'Z';

更新：

如果您使用的是MySQL 。 这是MySQL更新

UPDATE wp_posts WP 
   LEFT JOIN wp_postmeta WPM ON WP.post_id = WPM.post_id
SET WP.post_date = REPLACE(WPM.post_date, 'X', 'Y') 
WHERE meta_value = 'Z';

Answer 2

SQL服务器

UPDATE wp_posts 
post_date = REPLACE (post_date, 'X', 'Y')
FROM wp_posts WP LEFT OUTER JOIN wp_postmeta WPM ON WP.post_id = WPM.post_id
WHERE meta_value = 'Z';

MySQL的

UPDATE wp_posts 
LEFT JOIN wp_postmeta WPM ON WP.post_id = WPM.post_id 
SET post_date = REPLACE (post_date, 'X', 'Y')
WHERE meta_value = 'Z'

Answer 3

 UPDATE wp_posts SET post_date = REPLACE (WPM.post_date, 'X', 'Y')
 FROM wp_posts AS WP
 LEFT OUTER JOIN wp_postmeta AS WPM ON WP.post_id = WPM.post_id
 WHERE WP.meta_value = 'Z'