需要帮助 INNER JOIN 多个表并使用 MySQL 中的最后一个值行

Question

我有 3 个表如下：

|id| |uid| |tid|

曲目

|id| |uid|

通知

|id| |from| |tox|

如何让 UPDATE notifications 和 SET tox 等于其相对 tracks.id 的 tracks.uid 等于最后一个 comments.tid 值？

我试过了没有成功：

UPDATE notifications SET tox = (
  SELECT uid FROM tracks 
  INNER JOIN comments ON tracks.id = comments.tid ORDER BY comments.tid DESC LIMIT 1
  WHERE comments.tid=tracks.id)
WHERE tox = 0 ORDER BY id DESC LIMIT 1;

更新

首先，我按照建议编辑并移动了最后的 ORDER BY。之后我得到了一个不同的错误 1052 - Column 'typeid' in field list is ambiguous。

我这样解决的：

UPDATE `notifications` SET `tox` = (
  SELECT tracks.uid FROM `tracks` 
  INNER JOIN `comments` ON tracks.id = comments.tid 
  ORDER BY comments.id DESC LIMIT 1)
WHERE `tox` = 0 ORDER BY `id` DESC LIMIT 1;

Answer 1

我认为你的问题是子查询的语法：

UPDATE notifications
    SET tox = (SELECT uid
               FROM tracks INNER JOIN
                    comments
                    ON tracks.id = comments.tid
               WHERE comments.tid=tracks.id
               ORDER BY comments.tid DESC
               LIMIT 1
              )
    WHERE tox = 0
    ORDER BY id DESC
    LIMIT 1;

ORDER BY 总是在 WHERE 之后。

需要帮助 INNER JOIN 多个表并使用 MySQL 中的最后一个值行

Need help to INNER JOIN multiple tables and use last value row in MySQL

mysql

inner-join