SQL DateDiff advanced usage? - sql

Question

I need to calculate the DateDiff (hours) between two dates, but only during business-hours (8:30 - 16:00, no weekends). This result will then be put into the Reaction_Time column as per the example below.
ID Date Reaction_Time Overdue
1 29.04.2003 15:00:00
1 30.04.2003 11:00:00 3:30
2 30.04.2003 14:00:00
2 01.05.2003 14:00:00 7:30 YES
*Note: I didn't check to see if the dates in example were holidays.
I'm using SQL Server 2005
This will be combined with a bigger query, but for now all I need is this to get started, I'll try to figure out how to put it all together on my own. Thanks for the help!
Edit: Hey, thanks everyone for the replies. But due to the obvious complexity of a solution on SQL side, it was decided we would do this in Excel instead as that's where the report will be moved anyway. Sorry for the trouble, but I really figured it would be simpler than this. As it is, we just don't have the time.

Answer 1

I would recommend building a user defined function that calculates the date difference in business hours according to your rules.
SELECT
Id,
MIN(Date) DateStarted,
MAX(Date) DateCompleted,
dbo.udfDateDiffBusinessHours(MIN(Date), MAX(Date)) ReactionTime
FROM
Incident
GROUP BY
Id
I'm not sure where your Overdue value comes from, so I left it off in my example.
In a function you can write way more expressive SQL than in a query, and you don't clog your query with business rules, making it hard to maintain.
Also a function can easily be reused. Extending it to include support for holidays (I'm thinking of a Holidays table here) would not be too hard. Further refinements are possible without the need to change hard to read nested SELECT/CASE WHEN constructs, which would be the alternative.
If I have time today, I'll look into writing an example function.
EDIT: Here is something with bells and whistles, calculating around weekends transparently:
ALTER FUNCTION dbo.udfDateDiffBusinessHours (
#date1 DATETIME,
#date2 DATETIME
) RETURNS DATETIME AS
BEGIN
DECLARE #sat INT
DECLARE #sun INT
DECLARE #workday_s INT
DECLARE #workday_e INT
DECLARE #basedate1 DATETIME
DECLARE #basedate2 DATETIME
DECLARE #calcdate1 DATETIME
DECLARE #calcdate2 DATETIME
DECLARE #cworkdays INT
DECLARE #cweekends INT
DECLARE #returnval INT
SET #workday_s = 510 -- work day start: 8.5 hours
SET #workday_e = 960 -- work day end: 16.0 hours
-- calculate Saturday and Sunday dependent on SET DATEFIRST option
SET #sat = CASE ##DATEFIRST WHEN 7 THEN 7 ELSE 7 - ##DATEFIRST END
SET #sun = CASE ##DATEFIRST WHEN 7 THEN 1 ELSE #sat + 1 END
SET #calcdate1 = #date1
SET #calcdate2 = #date2
-- #date1: assume next day if start was after end of workday
SET #basedate1 = DATEADD(dd, 0, DATEDIFF(dd, 0, #calcdate1))
SET #calcdate1 = CASE WHEN DATEDIFF(mi, #basedate1, #calcdate1) > #workday_e
THEN #basedate1 + 1
ELSE #calcdate1
END
-- #date1: if Saturday or Sunday, make it next Monday
SET #basedate1 = DATEADD(dd, 0, DATEDIFF(dd, 0, #calcdate1))
SET #calcdate1 = CASE DATEPART(dw, #basedate1)
WHEN #sat THEN #basedate1 + 2
WHEN #sun THEN #basedate1 + 1
ELSE #calcdate1
END
-- #date1: assume #workday_s as the minimum start time
SET #basedate1 = DATEADD(dd, 0, DATEDIFF(dd, 0, #calcdate1))
SET #calcdate1 = CASE WHEN DATEDIFF(mi, #basedate1, #calcdate1) < #workday_s
THEN DATEADD(mi, #workday_s, #basedate1)
ELSE #calcdate1
END
-- #date2: assume previous day if end was before start of workday
SET #basedate2 = DATEADD(dd, 0, DATEDIFF(dd, 0, #calcdate2))
SET #calcdate2 = CASE WHEN DATEDIFF(mi, #basedate2, #calcdate2) < #workday_s
THEN #basedate2 - 1
ELSE #calcdate2
END
-- #date2: if Saturday or Sunday, make it previous Friday
SET #basedate2 = DATEADD(dd, 0, DATEDIFF(dd, 0, #calcdate2))
SET #calcdate2 = CASE DATEPART(dw, #calcdate2)
WHEN #sat THEN #basedate2 - 0.00001
WHEN #sun THEN #basedate2 - 1.00001
ELSE #date2
END
-- #date2: assume #workday_e as the maximum end time
SET #basedate2 = DATEADD(dd, 0, DATEDIFF(dd, 0, #calcdate2))
SET #calcdate2 = CASE WHEN DATEDIFF(mi, #basedate2, #calcdate2) > #workday_e
THEN DATEADD(mi, #workday_e, #basedate2)
ELSE #calcdate2
END
-- count full work days (subtract Saturdays and Sundays)
SET #cworkdays = DATEDIFF(dd, #basedate1, #basedate2)
SET #cweekends = #cworkdays / 7
SET #cworkdays = #cworkdays - #cweekends * 2
-- calculate effective duration in minutes
SET #returnval = #cworkdays * (#workday_e - #workday_s)
+ #workday_e - DATEDIFF(mi, #basedate1, #calcdate1)
+ DATEDIFF(mi, #basedate2, #calcdate2) - #workday_e
-- return duration as an offset in minutes from date 0
RETURN DATEADD(mi, #returnval, 0)
END
The function returns a DATETIME value meant as an offset from date 0 (which is "1900-01-01 00:00:00"). So for example a timespan of 8:00 hours would be "1900-01-01 08:00:00" and 25 hours would be "1900-01-02 01:00:00". The function result is the time difference in business hours between two dates. No special handling/support for overtime.
SELECT dbo.udfDateDiffBusinessHours('2003-04-29 15:00:00', '2003-04-30 11:00:00')
--> 1900-01-01 03:30:00.000
SELECT dbo.udfDateDiffBusinessHours('2003-04-30 14:00:00', '2003-05-01 14:00:00')
--> 1900-01-01 07:30:00.000
The function assumes the start of the next available work day (08:30 h) when the #date1 is off-hours, and the end of the previous available work day (16:00 h) when #date2 is off-hours.
"next/previous available" means:
if #date1 is '2009-02-06 07:00:00' (Fri), it will become '2009-02-06 08:30:00' (Fri)
if #date1 is '2009-02-06 19:00:00' (Fri), it will become '2009-02-09 08:30:00' (Mon)
if #date2 is '2009-02-09 07:00:00' (Mon), it will become '2009-02-06 16:00:00' (Fri)
if #date2 is '2009-02-09 19:00:00' (Mon), it will become '2009-02-09 16:00:00' (Mon)

Answer 2

DECLARE #BusHourStart DATETIME, #BusHourEnd DATETIME
SELECT #BusHourStart = '08:30:00', #BusHourEnd = '16:00:00'
DECLARE #BusMinutesStart INT, #BusMinutesEnd INT
SELECT #BusMinutesStart = DATEPART(minute,#BusHourStart)+DATEPART(hour,#BusHourStart)*60,
#BusMinutesEnd = DATEPART(minute,#BusHourEnd)+DATEPART(hour,#BusHourEnd)*60
DECLARE #Dates2 TABLE (ID INT, DateStart DATETIME, DateEnd DATETIME)
INSERT INTO #Dates2
SELECT 1, '15:00:00 04/29/2003', '11:00:00 04/30/2003' UNION
SELECT 2, '14:00:00 04/30/2003', '14:00:00 05/01/2003' UNION
SELECT 3, '14:00:00 05/02/2003', '14:00:00 05/06/2003' UNION
SELECT 4, '14:00:00 05/02/2003', '14:00:00 05/04/2003' UNION
SELECT 5, '07:00:00 05/02/2003', '14:00:00 05/02/2003' UNION
SELECT 6, '14:00:00 05/02/2003', '23:00:00 05/02/2003' UNION
SELECT 7, '07:00:00 05/02/2003', '08:00:00 05/02/2003' UNION
SELECT 8, '22:00:00 05/02/2003', '23:00:00 05/03/2003' UNION
SELECT 9, '08:00:00 05/03/2003', '23:00:00 05/04/2003' UNION
SELECT 10, '07:00:00 05/02/2003', '23:00:00 05/02/2003'
-- SET DATEFIRST to U.S. English default value of 7.
SET DATEFIRST 7
SELECT ID, DateStart, DateEnd, CONVERT(VARCHAR, Minutes/60) +':'+ CONVERT(VARCHAR, Minutes % 60) AS ReactionTime
FROM (
SELECT ID, DateStart, DateEnd, Overtime,
CASE
WHEN DayDiff = 0 THEN
CASE
WHEN (MinutesEnd - MinutesStart - Overtime) > 0 THEN (MinutesEnd - MinutesStart - Overtime)
ELSE 0
END
WHEN DayDiff > 0 THEN
CASE
WHEN (StartPart + EndPart - Overtime) > 0 THEN (StartPart + EndPart - Overtime)
ELSE 0
END + DayPart
ELSE 0
END AS Minutes
FROM(
SELECT ID, DateStart, DateEnd, DayDiff, MinutesStart, MinutesEnd,
CASE WHEN(#BusMinutesStart - MinutesStart) > 0 THEN (#BusMinutesStart - MinutesStart) ELSE 0 END +
CASE WHEN(MinutesEnd - #BusMinutesEnd) > 0 THEN (MinutesEnd - #BusMinutesEnd) ELSE 0 END AS Overtime,
CASE WHEN(#BusMinutesEnd - MinutesStart) > 0 THEN (#BusMinutesEnd - MinutesStart) ELSE 0 END AS StartPart,
CASE WHEN(MinutesEnd - #BusMinutesStart) > 0 THEN (MinutesEnd - #BusMinutesStart) ELSE 0 END AS EndPart,
CASE WHEN DayDiff > 1 THEN (#BusMinutesEnd - #BusMinutesStart)*(DayDiff - 1) ELSE 0 END AS DayPart
FROM (
SELECT DATEDIFF(d,DateStart, DateEnd) AS DayDiff, ID, DateStart, DateEnd,
DATEPART(minute,DateStart)+DATEPART(hour,DateStart)*60 AS MinutesStart,
DATEPART(minute,DateEnd)+DATEPART(hour,DateEnd)*60 AS MinutesEnd
FROM (
SELECT ID,
CASE
WHEN DATEPART(dw, DateStart) = 7
THEN DATEADD(SECOND, 1, DATEADD(DAY, DATEDIFF(DAY, 0, DateStart), 2))
WHEN DATEPART(dw, DateStart) = 1
THEN DATEADD(SECOND, 1, DATEADD(DAY, DATEDIFF(DAY, 0, DateStart), 1))
ELSE DateStart END AS DateStart,
CASE
WHEN DATEPART(dw, DateEnd) = 7
THEN DATEADD(SECOND, -1, DATEADD(DAY, DATEDIFF(DAY, 0, DateEnd), 0))
WHEN DATEPART(dw, DateEnd) = 1
THEN DATEADD(SECOND, -1, DATEADD(DAY, DATEDIFF(DAY, 0, DateEnd), -1))
ELSE DateEnd END AS DateEnd FROM #Dates2
)Weekends
)InMinutes
)Overtime
)Calculation

Answer 3

select datediff(hh,#date1,#date2) - 16.5*(datediff(dd,#date1,#date2))
The only catch is that it will give you 3:30 as 3.5 hours but you can fix that easily.

Answer 4

Use this code : to find out weekend in between dates
(
DATEDIFF(dd, open_date, zassignment_date) + 1
- ( (DATEDIFF(dd, open_date, zassignment_date) + 1)
-(DATEDIFF(wk, open_date, zassignment_date) * 2)
-(CASE WHEN DATENAME(dw, open_date) = 'Sunday' THEN 1 ELSE 0 END)
-(CASE WHEN DATENAME(dw, zassignment_date) = 'Saturday' THEN 1 ELSE 0 END) )) wk_end

Answer 5

Assuming you have a reference-table of the working days (and their hours), then I would use a 3 stage approach (pseudo-sql)
(first preclude the "all in one day" trivial example, since that simplifies the logic)
-- days that are neither the start nor end (full days)
SELECT #FullDayHours = SUM(day start to day end)
FROM reference-calendar
WHERE Start >= midnight-after-start and End <= midnight-before-end
-- time after the [query start] to the end of the first working day
SELECT #FirstDayHours = [query start] to day end
FROM reference-calandar
WHERE start day
-- time from the start of the last working day to the [query end]
SELECT #LastDayHours = day start to [query end]
FROM reference-calendar
WHERE end-day
IF #FirstDayHours < 0 SET #FirstDayHours = 0 -- starts outside working time
IF #LastDayHours < 0 SET #LastDayHours = 0 -- ends outside working time
PRINT #FirstDayHours + #FullDayHours + #LastDayHours
Obviously it is a bit hard to do properly without more context...

Answer 6

This function will give you the difference in business hours between two given times. This will return the difference in minutes or hours based on the date part parameter.
CREATE FUNCTION [dbo].[fnBusinessHoursDateDiff] (#StartTime SmallDatetime, #EndTime SmallDateTime, #DatePart varchar(2)) RETURNS DECIMAL (10,2)
AS
BEGIN
DECLARE #Minutes bigint
, #FinalNumber Decimal(10,2)
-- // Create Minute By minute table for CTE
-- ===========================================================
;WITH cteInputHours (StartTime, EndTime, NextTime) AS (
SELECT #StartTime
, #EndTime
, dateadd(mi, 1, #StartTime)
),
cteBusinessMinutes (TimeOfDay, [isBusHour], NextTime) AS(
SELECT StartTime [TimeOfDay]
, case when datepart(dw, StartTime) between 2 and 6 and convert(time,StartTime) between '08:30' and '15:59' then 1 else 0 end [isBusHour]
, dateadd(mi, 1, #StartTime) [NextTime]
FROM cteInputHours
UNION ALL
SELECT dateadd(mi, 1, (a.TimeOfDay)) [TimeOfDay]
, case when datepart(dw, a.TimeOfDay) between 2 and 6 and convert(time,dateadd(mi, 1, (a.TimeOfDay)) ) between '08:30' and '15:59' then 1 else 0 end [isBusHour]
, dateadd(mi, 2, (a.TimeOfDay)) NextTime
FROM cteBusinessMinutes a
WHERE dateadd(mi, 1, (a.TimeOfDay)) < #EndTime
)
SELECT #Minutes = count(*)
FROM cteBusinessMinutes
WHERE isBusHour = 1
OPTION (MAXRECURSION 0);
-- // Final Select
-- ===========================================================
SELECT #FinalNumber = #Minutes / (case when #DatePart = 'hh' then 60.00 else 1 end)
RETURN #FinalNumber
END