多个左连接已影响我的SUM(TIMESTAMPDIFF计算

时间:2013-04-10 14:35:17

标签: mysql sql left-join

我目前正在尝试创建一份报告,说明我的PHPBB3论坛上的某些人在上周预订的总时间。最初,我有以下查询按预期工作:

SELECT forum_users.username, SUM(TIMESTAMPDIFF(SECOND, schedule_slots.time_starting, schedule_slots.time_finishing)) AS seconds 
FROM forum_users 
LEFT JOIN schedule_slots 
    ON forum_users.user_id = schedule_slots.user_id 
    AND schedule_slots.time_starting >= (CURDATE() - INTERVAL 1 WEEK) 
    AND schedule_slots.is_del = 0 
    AND schedule_slots.channel = 0
WHERE (forum_users.group_id = 8 OR forum_users.group_id = 5 OR forum_users.group_id = 14) 
GROUP BY forum_users.username 
ORDER BY upper(forum_users.username)

但是,当我去加入另一个表时,时间戳差异最终被错误计算(它更高),这是我的新工作语句:

SELECT forum_users.username, SUM(TIMESTAMPDIFF(SECOND, schedule_slots.time_starting, schedule_slots.time_finishing)) AS seconds, group_concat(DISTINCT forum_user_group.group_id) AS user_groups 
FROM forum_users 
LEFT JOIN schedule_slots 
    ON forum_users.user_id = schedule_slots.user_id 
    AND schedule_slots.time_starting >= (CURDATE() - INTERVAL 1 WEEK) 
    AND schedule_slots.is_del = 0 
    AND schedule_slots.channel = 0 
LEFT JOIN forum_user_group 
    ON forum_user_group.user_id = forum_users.user_id 
WHERE (forum_users.group_id = 8 OR forum_users.group_id = 5 OR forum_users.group_id = 14 OR forum_users.group_id = 12) 
GROUP BY forum_users.username 
ORDER BY upper(forum_users.username)

我在这个上面写了一个空白,非常感谢你的帮助。

1 个答案:

答案 0 :(得分:0)

正确计算时间戳差异,但您将其乘以用户所在的组数。

我会尝试:

SELECT forum_users.username, SUM(TIMESTAMPDIFF(SECOND, schedule_slots.time_starting, schedule_slots.time_finishing)) AS seconds, 
(select group_concat(DISTINCT group_id) from forum_user_group WHERE forum_user_group.user_id = forum_users.user_id) AS user_groups 
FROM forum_users 
LEFT JOIN schedule_slots 
ON forum_users.user_id = schedule_slots.user_id 
AND schedule_slots.time_starting >= (CURDATE() - INTERVAL 1 WEEK) 
AND schedule_slots.is_del = 0 
AND schedule_slots.channel = 0 
WHERE (forum_users.group_id = 8 OR forum_users.group_id = 5 OR forum_users.group_id = 14 OR forum_users.group_id = 12) 
GROUP BY forum_users.username, user_groups 
ORDER BY upper(forum_users.username)