Question

类似于社区的类别，群组和帖子。我需要选择与用户相关的所有帖子。这些关系是需要在我所属的任何组中创建的所有帖子。我用查询子查询来完成它。

现在，我想以某种方式优化它，所以我只有一个没有子查询的查询。唯一的问题，我不知道如何。此时，我正在寻求帮助。

SELECT ... /* Lot of stuff. */
FROM `posts`

JOIN `groups`
ON (`groups`.`id` = `posts`.`group_id`)

JOIN `users`
ON (`users`.`id` = `posts`.`user_id`)

WHERE `groups`.`id` IN (SELECT `group_id` FROM `group_members` WHERE `user_id` = '33') /* My sub-query. ID '33' is variable.*/
AND `posts`.`post_id` = 0 /* For only first level posts. */

如果您需要表结构，请询问。非常感谢您的建议！

Answer 1

SELECT ... /* Lot of stuff. */
FROM `posts`

JOIN `groups`
ON (`groups`.`id` = `posts`.`group_id`)

JOIN `users`
ON (`users`.`id` = `posts`.`user_id`)

JOIN `group_members`
ON (`groups`.`id` = `group_members`.`group_id`)

WHERE `group_members`.`user_id` = '33'
AND `posts`.`post_id` = 0 /* For only first level posts. */

应该做的伎俩。至少，它应该等同于问题中的查询 - 如果它是一致的，我不知道。

Answer 2

试试这个

SELECT ... /* Lot of stuff. */
FROM `posts`

JOIN `groups`
ON (`groups`.`id` = `posts`.`group_id`)

JOIN `users`
ON (`users`.`id` = `posts`.`user_id`)

inner join `group_members` on (`groups`.`id` = `group_members`.`group_id`)
Where `group_members`.`user_id` = '33' AND `posts`.`post_id` = 0

将此查询与子查询连接到一个查询中

2 个答案: