mysql - “on子句”中的未知列“user.id”

MySQL查询：

SELECT
    *,
    `message`.`status` as `message_status`,
    `message`.`id` as `message_id`,
    group_concat(response.response) as response,
    group_concat(response.id) as response_id,
    `message`.`user_id` as `sender`
FROM `message`
LEFT JOIN `pet_info` ON `pet_info`.`id` = `message`.`pet_id`
LEFT JOIN `response` ON `response`.`message_id` = `message`.`id`
LEFT JOIN `user` as sender ON `user`.`id` = `message`.`user_id`
LEFT JOIN `user` as receiver ON `user`.`id` = `message`.`owner_id`
WHERE `user_id` = '6'
AND `pet_id` = '6'
GROUP BY `message`.`id`

如何解决此错误？

最佳答案

您在别名表：

LEFT JOIN `user` as sender

这意味着，就查询的其余部分而言，没有user表。有一个sender表。因此，您需要在ON子句中使用别名：

LEFT JOIN `user` as sender ON `sender`.`id` = `message`.`user_id`