Question

我有两个查询 - 一个通过了解group_id选择post_id，另一个检查该用户是否在该组中。我试图优化它们 - 把它们放在一起，但它现在抛出一个错误......

SELECT COUNT(bio_community_group_members.id) AS count
FROM `bio_community_group_members`
JOIN `bio_community_posts`
    ON (`bio_community_posts`.`id` = `180`)
WHERE `bio_community_group_members`.`group_id` = 'bio_community_posts.group_id'
    AND `bio_community_posts`.`user_id` = '34'

它说：

'on子句'中的未知列'180'。

问题：我有这个条目！

表格结构：

bio_community_posts：

id，
user_id，
group_id，
其他东西;

bio_community_group_members：

id，
user_id，
group_id，
status，
其他东西;

如果status存在，我需要从bio_community_group_members检索count。 status这件事只是因为我不知道如何开始构建我的查询。：（

感谢您的建议。

修改

嗯...现在它可以工作.....但是任何想法如何优化这两个查询并得到一个也选择SELECT `group_id` FROM `bio_community_posts` WHERE `id` = 180 SELECT COUNT(id) AS count FROM `bio_community_group_members` WHERE `group_id` = 41 AND `user_id` = '34'？

SELECT `bio_community_group_members`.`status`
FROM `bio_community_group_members`
JOIN `bio_community_posts` ON `bio_community_posts`.`group_id` = `bio_community_group_members`.`group_id`
WHERE `bio_community_group_members`.`group_id` = 41
  AND `bio_community_group_members`.`user_id` = '34'
  AND `bio_community_posts`.`id` = '180'
GROUP BY `bio_community_group_members`.`status`

编辑＃2：

这就是我想要的：

SELECT `bio_community_group_members`.`status`
FROM `bio_community_group_members`
JOIN `bio_community_posts` ON `bio_community_posts`.`group_id` = `bio_community_group_members.group_id`
WHERE `bio_community_posts`.`id` = '180'
AND `bio_community_posts`.`user_id` = '34'

谢谢！：）

编辑＃3：

我想我需要这样的东西......

SELECT `bio_community_group_members`.`status`
FROM `bio_community_group_members`
JOIN `bio_community_posts` ON `bio_community_posts`.`group_id` = `bio_community_group_members`.`group_id`
WHERE `bio_community_posts`.`id` = '180'
AND `bio_community_posts`.`user_id` = '34'

可是：

[Err] 1054 - 'on clause'中的未知列'bio_community_group_members.group_id'。

编辑＃4：

刚刚在查询中发现了一个错误。这是最终的解决方案：

{{1}}

Answer 1

在180上删除后引号（？），我认为你的意思是'180'？同时删除其他列名称周围的单引号，如下所示：

SELECT COUNT(bio_community_group_members.id) AS count
FROM `bio_community_group_members`
JOIN `bio_community_posts`
    ON (`bio_community_posts`.`id` = '180') -- Replaced back- with single-quotes.
WHERE `bio_community_group_members`.`group_id` = `bio_community_posts.group_id` -- Replaced single- with back-quotes.
    AND `bio_community_posts`.`user_id` = '34'

OP编辑后编辑：

我不确定你在寻找什么样的优化，但我猜它是这样的？

SELECT COUNT(id) AS count, status
FROM `bio_community_group_members`
JOIN `bio_community_posts` ON `bio_community_posts`.`group_id` = `bio_community_group_members`.`group_id`
WHERE `bio_community_group_members`.`group_id` = 41
  AND `bio_community_group_members`.`user_id` = '34'
  AND `bio_community_posts`.`id` = '180'
GROUP BY `bio_community_group_members`.`status`

评论后修改： 修正了你的编辑3：

SELECT `bio_community_group_members`.`status`
FROM `bio_community_group_members`
JOIN `bio_community_posts` ON `bio_community_posts`.`group_id` = `bio_community_group_members`.`group_id`
WHERE `bio_community_posts`.`id` = '180'
AND `bio_community_posts`.`user_id` = '34'

Answer 2

删除`arround 180

 ON (`bio_community_posts`.`id` = 180)

查询优化问题

2 个答案: