mysql - mysql跨表删除

Question

当我执行以下查询时:

DELETE FROM wp_postmeta 
    WHERE post_id 
        NOT IN (
            SELECT post_id 
            FROM wp_postmeta a 
            INNER JOIN wp_sl_posts b 
            ON a.post_id = b.id
            )

我收到一条错误消息:

You can't specify target table 'wp_postmeta' for update in FROM clause  

我有点知道为什么，但我真的不知道执行该操作所需的语法。我已经根据此处和其他地方的答案尝试了几种不同的替代方案，但运气不好。

Answer 1

尝试

DELETE wp_postmeta 
FROM wp_postmeta 
left outer JOIN wp_sl_posts b ON a.post_id = b.id
WHERE b.post_id is null