Calculate time difference (only working hours) in minutes between two dates

Question

I need to calculate the number of \"active minutes\" for an event within a database. The start-time is well known.

The complication is that these active minutes sho

Answer 1

I started working with what Unreason posted and was a great start. I tested this is SQL Server and found not all time was being captured. I think the problem was primarily when the event started and ended the same day. This solution seems to be working well enough for me

CREATE TABLE [dbo].[working_hours](
[wh_id] [int] IDENTITY(1,1) NOT FOR REPLICATION NOT NULL,
[wh_starttime] [datetime] NULL,
[wh_endtime] [datetime] NULL,
PRIMARY KEY CLUSTERED 
(
[wh_id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF,           ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

CREATE FUNCTION [dbo].[udFWorkingMinutes] 
(
@startdate DATETIME
,@enddate DATETIME
)
RETURNS INT
AS
BEGIN


DECLARE @WorkingHours INT
SET @WorkingHours = 
(SELECT 
CASE WHEN COALESCE(SUM(duration),0) < 0 THEN 0 ELSE SUM(Duration) 
END AS Minutes
FROM 
(
    --All whole days
   SELECT ISNULL(DATEDIFF(mi,wh_starttime,wh_endtime),0) AS Duration
   FROM working_hours
   WHERE wh_starttime >= @startdate AND wh_endtime <= @enddate 
   UNION ALL
   --All partial days where event start after office hours and finish after office hours
   SELECT ISNULL(DATEDIFF(mi,@startdate,wh_endtime),0) AS Duration
   FROM working_hours
   WHERE @startdate > wh_starttime AND @enddate >= wh_endtime 
   AND (CAST(wh_starttime AS DATE) = CAST(@startdate AS DATE))
   AND @startdate < wh_endtime
   UNION ALL
   --All partial days where event starts before office hours and ends before day end
   SELECT ISNULL(DATEDIFF(mi,wh_starttime,@enddate),0) AS Duration
   FROM working_hours
   WHERE @enddate < wh_endtime 
   AND @enddate >= wh_starttime
   AND @startdate <= wh_starttime 
   AND (CAST(wh_endtime AS DATE) = CAST(@enddate AS DATE))
   UNION ALL  
    --Get partial day where intraday event
   SELECT ISNULL(DATEDIFF(mi,@startdate,@enddate),0) AS Duration
   FROM working_hours
   WHERE @startdate > wh_starttime AND @enddate < wh_endtime 
   AND (CAST(@startdate AS DATE)= CAST(wh_starttime AS DATE))
   AND (CAST(@enddate AS DATE)= CAST(wh_endtime AS DATE))
 ) AS u)

 RETURN @WorkingHours
END
GO

Alls that is left to do is populate the working hours table with something like

;WITH cte AS (
SELECT CASE WHEN DATEPART(Day,'2014-01-01 9:00:00 AM') = 1 THEN '2014-01-01 9:00:00 AM' 
ELSE DATEADD(Day,DATEDIFF(Day,0,'2014-01-01 9:00:00 AM')+1,0) END AS      myStartDate,
CASE WHEN DATEPART(Day,'2014-01-01 5:00:00 PM') = 1 THEN '2014-01-01 5:00:00 PM' 
ELSE DATEADD(Day,DATEDIFF(Day,0,'2014-01-01 5:00:00 PM')+1,0) END AS myEndDate
UNION ALL
SELECT DATEADD(Day,1,myStartDate), DATEADD(Day,1,myEndDate)
FROM cte
WHERE DATEADD(Day,1,myStartDate) <=  '2015-01-01'
)
INSERT INTO working_hours
SELECT myStartDate, myEndDate
FROM cte
OPTION (MAXRECURSION 0)

delete from working_hours where datename(dw,wh_starttime) IN ('Saturday', 'Sunday')

--delete public holidays

delete from working_hours where CAST(wh_starttime AS DATE) = '2014-01-01'

My first post! Be merciful.