左连接的where子句中的Mysql查询错误

Posted 2023-03-14

【中文标题】左连接的where子句中的Mysql查询错误

【英文标题】：Mysql Query error in where clause on left join

【发布时间】：2015-08-01 14:54:25

【问题描述】：

对不起，基本问题：

select `plans`.`name`, `A`.`subscription_id`, `A`.`amount`, 
       `A`.`created_date`, `A`.`end_date`, 
       `A`.`subscription_status`, `users`.`email`, `A`.`plan_id`, 
       `A`.`user_id`, `usage`.`created_at` as `usagedate`,
        COUNT(usage.id) as used_count
from `subscriptions` A
left join `users` on `users`.`id` = `A`.`user_id` 
left join `plans` on `A`.`plan_id` = `plans`.`Id` 
left join `usage` on `A`.`user_id` = `usage`.`user_id` 
where `usage`.`created_at` between A.created_at and A.end_date
group by `A`.`plan_id`

我收到了错误

1054 - “where 子句”中的未知列“A.created_at”

【问题讨论】：

确定订阅表中有 created_at 列？

在select，你有A.created_date。

对愚蠢的错误和问题感到抱歉。否决票 :(

更重要的是，您的查询还有其他一些问题。 1) 将 WHERE 条件移动到 ON 子句以获得真正的 LEFT JOIN。现在它作为常规内部连接执行。 2) 您错过了在 GROUP BY 中指定几列。 （mysql 并不挑剔，我知道...）

@jarlh 感谢您的积分。我会改正的。

【参考方案1】：

我认为应该有A.created_date 而不是A.created_at

select `plans`.`name`, `A`.`subscription_id`, `A`.`amount`, 

`A`.`created_date`, `A`.`end_date`, 

`A`.`subscription_status`, `users`.`email`, `A`.`plan_id`, 

`A`.`user_id`, `usage`.`created_at` as `usagedate`, COUNT(usage.id) as 

used_count from `subscriptions`     A

left join `users` on `users`.`id` = `A`.`user_id` 

left join `plans` on `A`.`plan_id` = `plans`.`Id` 

left join `usage` on `A`.`user_id` = `usage`.`user_id` 

where 

`usage`.`created_at` between A.created_date and A.end_date

group by 

`A`.`plan_id`

【参考方案2】：

我想它应该是a.created_date

SELECT `p`.`name`, `A`.`subscription_id`, `A`.`amount`, `A`.`created_date`, `A`.`end_date`, `A`.`subscription_status`, `u`.`email`, `A`.`plan_id`, `A`.`user_id`, `us`.`created_at` AS `usagedate`, COUNT(`us`.`id`) AS `used_count` 
FROM `subscriptions` A
LEFT JOIN `users` u on `u`.`id` = `A`.`user_id` 
LEFT JOIN `plans` p on `A`.`plan_id` = `p`.`Id` 
LEFT JOIN `usage` us on `A`.`user_id` = `us`.`user_id` 
WHERE `us`.`created_at` between `A`.`created_date` and `A`.`end_date`
GROUP BY `A`.`plan_id`