TryCatchFinally.net Some SQL, some .NET, and whatever else

10Jan/131

Calculating working hours between two dates

As a follow-up to an earlier post (Return a list of all dates between a start and end date), I need to find the number of working hours between two timestamps - in this case, it was to see how long a support ticket had been open before it was initially assigned, but the user didn't want non-work hours to count against them.

To do this, I used the previous script to generate a list of dates and hours, and then marked the rows as work time or not (based on day of week and hour of day, evaluated together). The result was a table that would effectively let me do a SUM to find the value I was looking for. Once I had that table, I could join to it for rows between the two datetimes in question and SUM up rows that had "WorkTime" marked:

SELECT tt.TicketNumber,
       tt.TicketCreateTime,
       tt.TicketAssignTime,
       SUM(  CONVERT(INT, wh.WorkTime)) as WorkHoursBeforeAssigned
       COUNT(CONVERT(INT, wh.WorkTime)) as TotalHoursBeforeAssigned
  FROM TroubleTickets tt
  JOIN #WorkingHours wh
    ON wh.EvaluateTime BETWEEN tt.TicketCreateTime
                           AND tt.TicketAssignTime
GROUP BY tt.TicketNumber,
         tt.TicketCreateTime,
         tt.TicketAssignTime

In this case, tickets that were created and picked up after hours, without passing any worktime, would show as zero hours old (as they should, since they were interested in working time) - however, I've also included COUNT here to show total hours as well as work hours.

Also, this script only counts for raw day-of-week and hour-of-day working time - it ignores holidays and other special circumstances. I have a script that tracks holidays (American ones, at least), and I'll put that up shortly as well - if you want to take holidays into account, you could incorporate that into your evaluation.

Here's the script that builds the working time table (you can also download it here):

-- Set things up before we get started
--------------------------------------
DECLARE @WorkTimeStart		TINYINT,
		@WorkTimeEnd		TINYINT,
		@WorkDayOfWeekStart	TINYINT,
		@WorkDayOfWeekEnd	TINYINT

DECLARE @StartDate			DATETIME,
		@EndDate			DATETIME

CREATE TABLE #WorkingHours (
		EvaluateTime	DATETIME,
		IsWorktime		BIT DEFAULT(0)
)

--------------------------------------

	SET @WorkTimeStart = 7  --7AM
	SET @WorkTimeEnd   = 16 --4PM hour (4-5PM count as working)
	SET @WorkDayOfWeekStart = 2 --Monday
	SET @WorkDayOfWeekEnd   = 6 --Friday

	SET @StartDate	= '2000-01-01 00:00:00'
	SET @EndDate	= '2020-12-31 23:59:59'

--------------------------------------


-- Built the list of timestamps we're working with
;WITH numberlist(number)
   AS (SELECT RANK() over(order by c1.object_id,
                                   c1.column_id,
                                   c2.object_id,
                                   c2.column_id)
		 from sys.columns c1
        cross 
         join sys.columns c2)
INSERT INTO #WorkingHours (EvaluateTime)
SELECT DATEADD(hh, number-1, @StartDate)
  FROM numberlist
 WHERE DATEADD(hh, number-1, @StartDate) <= @EndDate


-- Set the times to worktime if they match criteria
UPDATE #WorkingHours
   SET IsWorktime = CASE WHEN (DATEPART(dw, EvaluateTime)
								BETWEEN @WorkDayOfWeekStart
								AND @WorkDayOfWeekEnd)
							  AND
							  (DATEPART(hh, EvaluateTime)
							   BETWEEN @WorkTimeStart
							   AND @WorkTimeEnd) THEN 1
						 ELSE 0
					END


-- Retun the results
 SELECT * FROM #WorkingHours
 ORDER BY EvaluateTime

 DROP TABLE #WorkingHours