Question

我有一个包含工人，车站和会话的数据库。会话描述了哪个工作人员在哪个工作站上。我设法构建了一个查询，它给出了每个会话重叠的持续时间。

SELECT 
        sA.station_id,
        sA.worker_id AS worker1, 
        sB.worker_id AS worker2, 
        SEC_TO_TIME(
            TIME_TO_SEC(LEAST(sA.end,sB.end)) - TIME_TO_SEC(GREATEST(sA.start,sB.start))
        ) AS overlap
    FROM 
        `sessions` AS sA, 
        `sessions` AS sB
    WHERE 
            sA.station_id = sb.station_id
        AND 
            sA.station_id = 6
        AND (
                sA.start BETWEEN sB.start AND sB.end
            OR 
                sA.end BETWEEN sB.start AND sB.end
        )

通过此查询，我得到一个像这样的结果

station_id  worker1     worker2     overlap
6             1               1     09:00:00
6             2               1     02:30:00
6             5               1     00:00:00
6             1               1     09:00:00
6             2               1     01:30:00
6             3               1     09:00:00
...
6             12              3     02:00:00
6             14              3     01:00:00
6             17              3     02:00:00
...

我现在想要的是总结worker1和worker2的每个组合的重叠，以获得整体重叠持续时间。

我尝试了使用SUM（）和GROUP BY的不同方法，但我从未得到想要的结果。

SELECT 
...
SEC_TO_TIME(
    **SUM**(TIME_TO_SEC(LEAST(sA.end,sB.end)) - TIME_TO_SEC(GREATEST(sA.start,sB.start)))
) AS overlap
...

#has as result
station_id  worker1 worker2 overlap
6   1   1   838:59:59

#in combination with
GROUP BY
    worker1

#i get
station_id  worker1 worker2 overlap
6   1   1   532:30:00
6   2   1   -33:00:00
6   3   1   270:30:00
6   5   1   598:30:00
6   6   1   542:00:00
6   7   1   508:00:00
6   8   5   53:00:00
6   9   1   54:30:00
6   10  1   310:00:00
6   11  1   -108:00:00
6   12  1   593:30:00
6   14  1   97:30:00
6   15  1   -53:30:00
6   17  1   293:30:00

最后的结果很接近，但我仍然缺少很多组合。我也不明白为什么会出现8 - 5组合。

感谢您的帮助（以及阅读时间）

Answer 1

aaargh，对不起我的愚蠢，解决方案很简单

....
SUM(((UNIX_TIMESTAMP(LEAST(sA.end,sB.end))-UNIX_TIMESTAMP(GREATEST(sA.start,sB.start)))/3600))
...
GROUP BY station_id, worker1, worker2            
ORDER BY worker1, worker2

我切换到使用时间戳并将其转换为/ 3600小时，因为我以前使用TIME_TO_SEC和SEC_TO_TIME的方法仅使用DATETIME字段的TIME部分，从而产生了一些错误的数字。使用MySQL 5.5，我可以使用TO_SECONDS但不幸的是我的服务器仍在运行5.1。

MySQL中2个外键的每个组合的重叠持续时间总和

1 个答案: