Calculating total time in a place with SQL Server

问题:

I am new to SQL and I was wondering if the following is even possible to achieve.

Using SQL Server 2012 I would like to find the total time a given entity has spent in one location in minutes. There are multiple entries for each entity as they may have gone in and out of a given location many times during the day, I just want to find the total time spent in minutes for all the time spent for a given location.

The table has two datetime columns that display Starttime and Endtime, along with location ID and Entity ID.

I have managed to find a way to work out the time difference between Starttime and Endtime for one event, but I want to sum for all those events in the location to be displayed as total time.

Please let me know if I need to give any more information

回答1:

What you need to do is to calculate the date difference between the locations where the entity had spent time, as below

SELECT
*
FROM MyTable

Result Values

Starttime               Endtime                 LocationID  EntityID
2014-09-23 14:07:43     2014-09-23 16:07:43     2           2
2014-09-23 14:09:03     2014-09-23 20:09:03     3           2
2014-09-23 14:09:51     2014-09-23 21:09:51     8           2
2014-09-23 14:15:10     2014-09-23 21:15:10     8           3
2014-09-23 14:15:16     2014-09-23 17:15:16     8           3
2014-09-23 14:15:23     2014-09-23 22:15:23     4           3
2014-09-23 14:15:32     2014-09-23 15:15:32     5           3
2014-09-23 14:06:26     2014-09-23 14:06:26     1           2

Use the below query to get the desired result

SELECT
    DATEDIFF(MINUTE, MIN(Starttime), MAX(Endtime)) TotalTimeSpentInMinutes,
    LocationID
FROM MyTable
WHERE EntityID = 2
GROUP BY LocationID

Result values would be

TotalTimeSpentInMinutes LocationID
0                       1
120                     2
360                     3
420                     8

回答2:

select LocationId , SUM(DATEDIFF(MINUTE, StartTime,EndTime))
from locationdatetime
group by LocationId