MySQL 总时间正在增加答案

【问题标题】：MySQL total time is compoundingMySQL 总时间正在增加
【发布时间】：2018-09-26 18:52:45
【问题描述】：

我有这个问题，

SELECT
    testTimes.reportId,
    testTimes.userID,
--  diff,
    SUM(diff) AS total
FROM
    (
    SELECT
        start_log.reportID,
        start_log.userID,
        start_log.testID,
        MAX(start_log.eventDateTime) AS start_time,
        end_log.eventDateTime AS end_time,
        TIMESTAMPDIFF(MINUTE,
        MAX(start_log.eventDateTime),
        end_log.eventDateTime) AS diff
    FROM
        testtracker_event AS start_log
    INNER JOIN testtracker_event AS end_log ON
        ( start_log.userID = end_log.userID
        AND start_log.reportID = end_log.reportID
        AND start_log.testID = end_log.testID
        AND end_log.eventDateTime > start_log.eventDateTime)
    WHERE
        (start_log.eventType = 'start'
        OR start_log.eventType = 'resume')
        AND (end_log.eventType = 'finish'
        OR end_log.eventType = 'pause')
        AND start_log.reportID = '20466'
    GROUP BY
        start_log.userID,
        start_log.testID,
        start_log.eventDateTime,
        start_log.reportID
    ORDER BY
        start_time DESC) testTimes

当针对这个数据集运行时；

|reportID|testID|eventDateTime|userID|eventType|workstation|note|  
|--------|------|-------------|------|---------|-----------|----|  
|20466|1|2018-04-26 14:41:42|msharpe|start| |           |  
|20466|1|2018-04-26 15:17:10|msharpe|finish| |            |  
|20466|1|2018-04-26 15:17:20|msharpe|reset| |"MIS-CLICK"|  
|20466|1|2018-04-26 15:17:21|msharpe|start| |           |  
|20466|1|2018-04-27 08:11:02|msharpe|finish| |            |  
|20466|2|2018-04-26 14:41:43|msharpe|start| |           |  
|20466|2|2018-04-27 08:11:02|msharpe|finish| |            |  
|20466|3|2018-04-26 14:42:15|msharpe|start| |           |  
|20466|3|2018-04-26 15:17:23|msharpe|finish| |            |  
|20466|4|2018-04-26 15:19:25|msharpe|start| |           |  
|20466|4|2018-04-26 15:34:59|msharpe|finish| |            |  
|20466|5|2018-04-26 14:42:21|msharpe|start| |           |  
|20466|5|2018-04-26 15:17:29|msharpe|finish| |            |  
|20466|7|2018-04-26 16:32:57|msharpe|start| |           |  
|20466|7|2018-04-27 08:11:03|msharpe|finish| |            |  
|20466|8|2018-04-26 15:38:29|msharpe|markna| |            |  
|20466|10|2018-04-27 12:05:21|msharpe|start| |           |  
|20466|10|2018-04-27 12:05:22|msharpe|finish| |           |  
|20466|16|2018-04-26 14:42:17|msharpe|start| |           |  
|20466|16|2018-04-26 15:17:28|msharpe|finish| |           |  
|20466|40|2018-04-26 14:42:17|msharpe|start| |           |  
|20466|40|2018-04-26 15:17:26|msharpe|finish| |           |  
|20466|50|2018-04-27 12:05:22|msharpe|start| |           |  
|20466|50|2018-04-27 12:05:23|msharpe|finish| |           |  
|20466|52|2018-04-27 08:50:54|msharpe|start| |           |  
|20466|52|2018-04-27 10:00:27|msharpe|finish| |           |  
|20466|53|2018-04-26 15:58:56|msharpe|start| |           |  
|20466|53|2018-04-26 16:32:56|msharpe|finish| |           |  
|20466|54|2018-04-26 15:38:24|msharpe|markna| |           |

RESULT - 20466  msharpe 3293

因此，我目前获得了 3,293 分钟，即使有并发调度和 2 个看起来像是在一夜之间签署了偶数的情况，我预计结果将非常大约 1845 年

我可以看到发生了一些重复，我猜这与join 有关但是我缺乏获得正确答案的经验或知识，在这种情况下，我找到了答案，我遇到了麻烦与这种情况相关。

虽然我知道有些人可能会想引用我的一个较早的问题 How would I update this MySQL query to get total elapsed time from start, stop, pause and resume events 这个问题 Calculating difference on datetime row betwen rows on the same table 作为重复项，我要问的是如何改进现有查询以不产生复合效果，和/或尽量减少重复。

SQLFiddle 很好，http://www.sqlfiddle.com/#!9/0dd34d/1

【问题讨论】：

所以答案不是 1284？
请说明您是如何得出 1845 年的（粗略）预期结果的。顺便说一下，没有resume 数据
只是通过查看数据并四舍五入在我的脑海中快速计算出来，认为我在做这件事时错过了一夜。这就是我指定一个非常粗略的原因。

标签： mysql

【解决方案1】：

在您现有的连接中，您将每个起点与多个终点相匹配，因此您将总数相乘。您需要将每个起点与下一个终点相匹配（一个起点，一个终点）。除非您运行的数据库版本支持 lead() over()，否则您可以使用相关子查询来实现这一点，如下所示：

SELECT
    start_log.reportID
  , start_log.userID
  , start_log.testID
  , start_log.eventDateTime AS start_time
  , start_log.end_time
  , TIMESTAMPDIFF(MINUTE,start_log.eventDateTime,start_log.end_time) AS diff
FROM (
        select
            s.*
            , (select f.eventDateTime from mytable f
                    WHERE s.userID = f.userID
                    AND s.reportID = f.reportID
                    AND s.testID = f.testID
                    AND f.eventType = 'finish'
                    AND f.eventDateTime > s.eventDateTime
               order by f.eventDateTime
               limit 1
               ) end_time
        from mytable as s
        where s.eventType = 'start'
       ) AS start_log

该查询的结果（使用提供的示例）是：

       reportID   userID    testID       start_time             end_time         diff  
 ---- ---------- --------- -------- --------------------- --------------------- ------ 
   1      20466   msharpe        1   26.04.2018 14:41:42   26.04.2018 15:17:10     35  
   2      20466   msharpe        1   26.04.2018 15:17:21   27.04.2018 08:11:02   1013  
   3      20466   msharpe        2   26.04.2018 14:41:43   27.04.2018 08:11:02   1049  
   4      20466   msharpe        3   26.04.2018 14:42:15   26.04.2018 15:17:23     35  
   5      20466   msharpe        4   26.04.2018 15:19:25   26.04.2018 15:34:59     15  
   6      20466   msharpe        5   26.04.2018 14:42:21   26.04.2018 15:17:29     35  
   7      20466   msharpe        7   26.04.2018 16:32:57   27.04.2018 08:11:03    938  
   8      20466   msharpe       10   27.04.2018 12:05:21   27.04.2018 12:05:22      0  
   9      20466   msharpe       16   26.04.2018 14:42:17   26.04.2018 15:17:28     35  
  10      20466   msharpe       40   26.04.2018 14:42:17   26.04.2018 15:17:26     35  
  11      20466   msharpe       50   27.04.2018 12:05:22   27.04.2018 12:05:23      0  
  12      20466   msharpe       52   27.04.2018 08:50:54   27.04.2018 10:00:27     69  
  13      20466   msharpe       53   26.04.2018 15:58:56   26.04.2018 16:32:56     34

虽然可能需要进一步改进，但这应该可以让您继续前进。

见：http://rextester.com/CWB43023

【讨论】：