MS Access 2010，如何计算两条记录之间的时间 - 相同的 ID，不同的时间

Question

我有一个记录列表，其中包含 AlarmID、System、State 和 Raised ON。

一个事件由两条记录表示，相同的AlarmID，第一个状态为开启，第二个状态为关闭，对应的时间。

这是我的查询：

SELECT *
FROM [Alarmi_On-Off]
WHERE [Alarmi_On-Off].[Alarm ID] IN (SELECT [Alarmi_On-Off].[Alarm ID] 
                                     FROM [Alarmi_On-Off]
                                     GROUP BY [Alarmi_On-Off].[Alarm ID] 
                                     HAVING COUNT([Alarmi_On-Off].[Alarm ID]) > 1);

结果：

+---------+---------+-------+------------------+
| AlarmID | System  | State |    Raised On     |
+---------+---------+-------+------------------+
|    1001 | System1 | On    | 16.08.2016 14:23 |
|    1001 | System1 | Off   | 16.08.2016 16:17 |
|    1002 | System2 | On    | 27.06.2016 12:14 |
|    1002 | System2 | Off   | 27.06.2016 12:24 |
|    1002 | System2 | On    | 14.07.2016 03:37 |
|    1002 | System2 | Off   | 14.07.2016 03:38 |
+---------+---------+-------+------------------+

我想创建一个查询来计算每个系统的开启和关闭状态之间的时间差，记住要排除所有事件少于 2 个的系统（在上面的示例中，排除 AlarmID 1001），我尝试使用“有 COUNT..”

在该查询中，我将有一条记录，而不是两条记录，其中包含系统和计算时间。

感谢任何帮助。

Answer 1

Access 中的语法（可能还有性能）对此将非常糟糕，但这样的东西应该可以工作：

SELECT AlarmID,System,
    (SELECT TOP 1 [Raised On] FROM [Alarmi_On-Off] 
     WHERE A.AlarmID = AlarmID 
     AND A.[Raised On] < [Raised On] 
     AND State = 'Off' ORDER BY [Raised On]) - [Raised On] AS Duration 
FROM [Alarmi_On-Off] AS A 
WHERE State = 'On' 
ORDER BY AlarmID,[Raised On]

请注意，Duration 值将是一个 Double，代表天数和小数天数。您可以将其转换为 Date 或使用 Access 的日期和时间函数根据需要提取日期和时间部分，即：

SELECT AlarmID,System,HOUR(Duration) AS Hours, MINUTE(Duration) AS Minutes FROM
(
SELECT AlarmID,System,
    (SELECT TOP 1 [Raised On] FROM [Alarmi_On-Off] 
     WHERE A.AlarmID = AlarmID 
     AND A.[Raised On] < [Raised On] 
     AND State = 'Off' ORDER BY [Raised On]) - [Raised On] AS Duration 
FROM [Alarmi_On-Off] AS A 
WHERE State = 'On' 
ORDER BY AlarmID,[Raised On]
) T

样本数据的结果：

AlarmID   System     Hours   Minutes
1001      System1    1       54
1002      System2    0       10
1002      System2    0       1

Answer 2

您可以使用以下查询来查找“On”和“Off”状态之间的时间差：

SELECT
    start_log.AlarmID,
    start_log.Rasied_On AS start_time,
    end_log.Rasied_On AS end_time,
    DATEDIFF(MINUTE, start_log.Rasied_On, end_log.Rasied_On) AS TimeInMin
FROM
    [Alarmi_On-Off] AS start_log
INNER JOIN
    [Alarmi_On-Off] AS end_log ON (
            start_log.AlarmID = end_log.AlarmID AND start_log.Rasied_On < end_log.Rasied_On)
WHERE start_log.State = 'On'
AND end_log.State = 'Off'
GROUP BY start_log.AlarmID, start_log.Rasied_On, end_log.Rasied_On

输出我的意思是时差以分钟为单位：