Calculating working minutes for Normal and Night Shift - sql

Question

I am making a query to fetch the working minutes for employees. The problem I have is the Night Shift. I know that I need to subtract the "ShiftStartMinutesFromMidnight" but I can't find the right logic.
NOTE: I can't changing the database, I only can use the data from it.
Let's say I have these records.
+----+--------------------------+----------+
| ID | EventTime | ReaderNo |
-----+--------------------------+----------+
| 1 | 2019-12-04 11:28:46.000 | In |
| 1 | 2019-12-04 12:36:17.000 | Out |
| 1 | 2019-12-04 12:39:23.000 | In |
| 1 | 2019-12-04 12:51:21.000 | Out |
| 1 | 2019-12-05 07:37:49.000 | In |
| 1 | 2019-12-05 08:01:22.000 | Out |
| 2 | 2019-12-04 22:11:46.000 | In |
| 2 | 2019-12-04 23:06:17.000 | Out |
| 2 | 2019-12-04 23:34:23.000 | In |
| 2 | 2019-12-05 01:32:21.000 | Out |
| 2 | 2019-12-05 01:38:49.000 | In |
| 2 | 2019-12-05 06:32:22.000 | Out |
-----+--------------------------+----------+
WITH CT AS (SELECT
EIn.PSNID, EIn.PSNNAME
,CAST(DATEADD(minute, -0, EIn.EventTime) AS date) AS dt
,EIn.EventTime AS LogIn
,CA_Out.EventTime AS LogOut
,DATEDIFF(minute, EIn.EventTime, CA_Out.EventTime) AS WorkingMinutes
FROM
VIEW_EVENT_EMPLOYEE AS EIn
CROSS APPLY
(
SELECT TOP(1) EOut.EventTime
FROM VIEW_EVENT_EMPLOYEE AS EOut
WHERE
EOut.PSNID = EIn.PSNID
AND EOut.ReaderNo = 'Out'
AND EOut.EventTime >= EIn.EventTime
ORDER BY EOut.EventTime
) AS CA_Out
WHERE
EIn.ReaderNo = 'In'
)
SELECT
PSNID
,PSNNAME
,dt
,LogIn
,LogOut
,WorkingMinutes
FROM CT
WHERE dt BETWEEN '2019-11-29' AND '2019-12-05'
ORDER BY LogIn
;
OUTPUT FROM QUERY
+----+------------+-------------------------+-------------------------+----------------+
| ID | date | In | Out | WorkingMinutes |
-----+------------+-------------------------+-------------------------+----------------+
| 1 | 2019-12-04 | 2019-12-04 11:28:46.000 | 2019-12-04 12:36:17.000 | 68 |
| 1 | 2019-12-04 | 2019-12-04 12:39:23.000 | 2019-12-04 12:51:21.000 | 12 |
| 1 | 2019-12-05 | 2019-12-05 07:37:49.000 | 2019-12-05 08:01:22.000 | 24 |
-----+------------+-------------------------+-------------------------+----------------+
I was thinking something like this. When Out is between 06:25 - 6:40. But I also need to check If employee, previous day has In between 21:50 - 22:30. I need that second condition because some employee from first shift maybe can Out, for example at 6:30.
*(1310 is the ShiftStartMinutesFromMidnight
Line 3 of Query
CAST(DATEADD(minute, -0, EIn.EventTime) AS date) AS dt
Updating the Line 3 with this code.
CASE
WHEN CAST(CA_Out.LogDate AS time) BETWEEN '06:25:00' AND '06:40:00'
AND CAST(EIn.LogDate AS time) BETWEEN '21:50:00' AND '22:30:00' THEN CAST(DATEADD(minute, -1310, EIn.LogDate) AS date)
ELSE CAST(DATEADD(minute, -0, EIn.LogDate) AS date)
END as dt
Expected Output
+----+------------+-------------------------+-------------------------+----------------+
| ID | date | In | Out | WorkingMinutes |
-----+------------+-------------------------+-------------------------+----------------+
| 2 | 2019-12-04 | 2019-12-04 22:11:46.000 | 2019-12-04 23:06:17.000 | 55 |
| 2 | 2019-12-04 | 2019-12-04 23:34:23.000 | 2019-12-05 01:32:21.000 | 118 |
| 2 | 2019-12-04 | 2019-12-05 01:38:49.000 | 2019-12-05 06:32:22.000 | 294 |
-----+------------+-------------------------+-------------------------+----------------+

Answer 1

Assuming that total minutes per separate date is enough:
WITH
/* enumerate pairs */
cte1 AS ( SELECT *,
COUNT(CASE WHEN ReaderNo = 'In' THEN 1 END)
OVER (PARTITION BY ID
ORDER BY EventTime) pair
FROM test ),
/* divide by pairs */
cte2 AS ( SELECT ID, MIN(EventTime) starttime, MAX(EventTime) endtime
FROM cte1
GROUP BY ID, pair ),
/* get dates range */
cte3 AS ( SELECT CAST(MIN(EventTime) AS DATE) minDate,
CAST(MAX(EventTime) AS DATE) maxDate
FROM test),
/* generate dates list */
cte4 AS ( SELECT minDate theDate
FROM cte3
UNION ALL
SELECT DATEADD(dd, 1, theDate)
FROM cte3, cte4
WHERE theDate < maxDate ),
/* add overlapped dates to pairs */
cte5 AS ( SELECT ID, starttime, endtime, theDate
FROM cte2, cte4
WHERE theDate BETWEEN CAST(starttime AS DATE) AND CAST(endtime AS DATE) ),
/* adjust borders */
cte6 AS ( SELECT ID,
CASE WHEN starttime < theDate
THEN theDate
ELSE starttime
END starttime,
CASE WHEN CAST(endtime AS DATE) > theDate
THEN DATEADD(dd, 1, theDate)
ELSE endtime
END endtime,
theDate
FROM cte5 )
/* calculate total minutes per date */
SELECT ID,
theDate,
SUM(DATEDIFF(mi, starttime, endtime)) workingminutes
FROM cte6
GROUP BY ID,
theDate
ORDER BY 1,2
fiddle
The solution is specially made detailed, step by step, so that you can easily understand the logic.
You may freely combine some CTEs into one. You may also use pre-last cte5 combined with cte2 if you need the output strongly as shown.
The solution assumes that none records are lost in source data (each 'In' matches strongly one 'Out' and backward, and no adjacent or overlapped pairs).

Answer 2

Don't know where you stopped but here is how I do,
Night shift 20:00 - 05:00 so in one day 00:00 - 5:00; 22:00 - 24:00
day shift 5:00 - 22:00
To get easier overlapping checking you need to change all dates to unix timestamp. so you don't have to split time intervals like shown above
So generate map of each period work for fetch period date_from and date_till, make sure to add holiday and pre-holiday exceptions where periods are different
something like:
Unix values is only for understanding.
unix_from_tim, unix_till_tim, shift_type
1580680800, 1580680800, 1 => example 02-02-2020:22:00:00, 03-02-2020:05:00:00, 1
1580680800, 1580680800, 0 => example 03-02-2020:05:00:00, 03-02-2020:22:00:00, 0
1580680800, 1580680800, 1 => example 03-02-2020:22:00:00, 04-02-2020:05:00:00, 1
...
Make sure you don't calculate overlapping minutes on period start/end..
And there is worker one row
with unix_from_tim, unix_from_tim
1580680800, 1580680800=> something like 02-02-2020:16:30:00, 03-02-2020:07:10:00
When you check overlapping you can get ms like this:
MIN(work_period:till,worker_period:till) - MAX(work_period:from, worker_period:from);
example in simple numbers:
work_period 3 - 7
worker_period 5 - 12
MIN(7,12) - MAX(3,5) = 7 - 5 = 2 //overlap
work_period 3 - 7
worker_period 8 - 12
MIN(7,12) - MAX(3,8) = 7 - 8 = -1 //if negative not overlap!
work_period 3 - 13
worker_period 8 - 12
MIN(13,12) - MAX(3,8) = 13 - 8 = 5 //full overlap!
And you have to check each worker period on all overlaping time generated work intervals.
May be someone can make select where you don't have to generate work_shift overlapping but its not a easy task if you add more holidays, transferred days, reduced time days etc.
Hope it helps