Question

我正在尝试构建一个聊天应用程序，其中我有这四个表

chat - id，group_id，body，time_posted [timestamp]
chat_groups - 建立ID，群组名称
users_groups - 将用户链接到一个组，还定义用户是否盯着这个组FIELDS :: user_id，group_id，stared [bool]
wall_visit --user_id，group_id，last_visit [timestamp]

这个想法是每个用户加入一个群组，然后他们在聊天中发帖。 chat_groups表仅用于定义房间，而users_groups用于设置对该组成员的访问权。

wall_visit表是一个表，用于存储上次访问特定组的特定用户（因为它知道的很多人都知道..）

现在我想要建立的是进入一个查询，

与{/ li>相关的chat_groups用户
自用户上次登录（来自设置）以来发布到此论坛的邮件数
此群组中的成员数
群组名称

:) 我现在已经尝试了几个小时:(最好我能想出来

SELECT w.last_visit,access.stared,cg.user_id,u.fullname as username,cg.name as group_name ,cgu.count_members,c.count_msgs,c.time_posted
            FROM `chat_groups`cg
            inner join chat_groups_users access on (access.group_id = cg.id and access.user_id = ?)
            left outer join users u on u.id = cg.user_id
            left join wall_visit w on w.group_id = cg.id
            left  join (select count(*) as count_members,group_id from group_users group by group_id) cgu on cgu.group_id = cg.id
            left join (SELECT count(wv.id) as count_msgs,c.group_id,c.time_posted FROM chats c
left outer join `wall_visit` wv on (wv.group_id is not null and c.group_id = wv.group_id and c.time_posted > wv.last_visit)
group by c.group_id) c on c.group_id = cg.id
            where cg.user_id = 1

此查询正在运行..是，我的主要问题是自上次访问以来该组中的邮件计数。

使message_count工作的最佳方法是什么:( ??
可以更优化此查询吗？

感谢SO社区：）

我的第二次尝试

SELECT w.last_visit,access.stared,cg.user_id,u.fullname as username,cg.with_id,uu.fullname as with_name,cg.name as group_name ,cgu.count_members,c.count_msgs,c.time_posted
            FROM `chat_groups`cg
            inner join chat_groups_users access on (access.group_id = cg.id and access.user_id = 1)
            left outer join users u on u.id = cg.user_id
            left join wall_visit w on w.chat_id = cg.id
            left outer join users uu on uu.id = cg.with_id
            left  join (select count(*) as count_members,group_id from chat_groups_users group by group_id) cgu on cgu.group_id = cg.id
            left join (
            SELECT group_id,count(c.id) as count_msgs,time_posted FROM `chats` c inner join wall_Visit wv on wv.chat_id = c.group_id where c.id > wv.last_visit group by c.group_id
            ) c on c.group_id = cg.id
            where cg.user_id = 1

Answer 1

这应该可以解决你的消息问题

SELECT 

    `cg`.`user_id`, `cg`.`with_id`, `cg`.`name` AS `group_name`,
    `access`.`stared`,
    `u`.`fullname` AS `username`,
    `w`.`last_visit`,    
    `uu`.`fullname` AS `with_name`, 
    `cgu`.`count_members`, 
    `c`.`count_msgs`, `c`.`time_posted`

FROM `chat_groups` AS `cg`
INNER JOIN `chat_groups_users` AS `access` 
            ON (`access`.`group_id` = `cg`.`id` AND `access`.`user_id` = `cg`.`user_id`)
LEFT OUTER JOIN `users` AS `u` 
            ON (`u`.`id` = `cg`.`user_id`)
LEFT JOIN `wall_visit` AS `w` 
            ON (`w`.`chat_id` = `cg`.`id`)
LEFT OUTER JOIN `users` AS `uu` 
            ON (`uu`.`id` = `cg`.`with_id`)
LEFT JOIN (
    SELECT COUNT(*) AS `count_members`, `group_id` 
    FROM `chat_groups_users` 
    GROUP BY 
        `group_id`
) AS `cgu` 
            ON (`cgu`.`group_id` = `cg`.`id`)
LEFT JOIN (
    SELECT count(`c`.`id`) AS `count_msgs`, `c`.`time_posted` 
    FROM `chats` AS `c` 
    INNER JOIN `wall_visit` AS `wv` 
            ON (`wv`.`chat_id` = `c`.`group_id`) 
    WHERE 
        `c`.`time_posted` > `wv`.`last_visit` 
    GROUP BY 
        `c`.`group_id`
) AS `c` 
            ON (`c`.`group_id` = `cg`.`id`)
WHERE `cg`.`user_id` = 1

否则你必须设置一个小提琴

使用3个表从连接计数mysql

1 个答案: