查询 Wordpress 数据库时出现 MySQL LEFT JOIN 错误 1064

问题描述：

我正在尝试从 Wordpress 数据库中检索一些数据:

I'm trying to retrieve some data from a Wordpress database:

SELECT M.meta_value,wp_users.ID
FROM wp_postmeta AS M 
WHERE meta_key = "_from_email" AND post_id = 277124
LEFT JOIN wp_users ON M.meta_value = wp_users.user_email

在这里，我的目的是获取 wp_users 用户的 ID，该用户的 email 与 meta_value代码>.

Here, my intention is to get the ID of the wp_users user who has an email identical to one in meta_value.

但我收到以下错误:

1064 - 您的 SQL 语法有错误；检查与您的 MySQL 服务器版本相对应的手册，了解在LEFT JOIN wp_users ON M.meta_value = wp_users.user_email

1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LEFT JOIN wp_users ON M.meta_value = wp_users.user_email

您是否看到任何语法错误?

Do you see any syntax error?

答

left join 必须在 where 子句之前声明

left join must be declare before where clause

SELECT M.meta_value,wp_users.ID
FROM wp_postmeta AS M 
LEFT JOIN wp_users ON M.meta_value = wp_users.user_email
WHERE meta_key = "_from_email" AND post_id = 277124

确保您没有在 where 子句中使用左连接表的列，否则这意味着连接作为内部连接工作......最终将这些列移动到相关的 ON 子句中

查询 Wordpress 数据库时出现 MySQL LEFT JOIN 错误 1064

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