SQL Business Hours Calculation Error - sql

Question

Hoping someone can tell me where I am going wrong here, I started with a Business Hours query found at Calculate business hours between two dates, it's the second top answer because the top answer was not providing the correct output upon testing. The issue I am having is when I cross over to a new day and the end datetime exceeds the Business Day End. Here is my test:
select dbo.BusinessSeconds('09:00:00','17:00:00','2014-12-24 16:59:59','2014-12-26 18:00:00');
So if I go from 1 second before COB to the start of the next day, I get 1 second, which is correct. If I go from the same start to the end of the day the next day, I get 28801, or 1 full day and 1 second - which is also correct. However, if I extend the date end time to 17:00:01 through 17:59:59 it also includes those seconds but if I hit 18:00:00, the time truncates back to the original 17:00:00 end of day. So I will get correct data for any given end time unless it is during the 17:00:00-17:59:59 timeframes and then I potentially get up to an extra hour of time that I should not have.
Any help would be greatly appreciated as I have a deliverable on this by tomorrow.
ALTER Function [dbo].[BusinessSeconds](#BusinessDayStart TIME,#BusinessDayEnd TIME,#StartDate DATETIME,#EndDate DATETIME) Returns Int
AS
Begin
--TEST: select dbo.BusinessSeconds('09:00:00','17:00:00','2014-12-24 16:59:59','2014-12-26 18:00:00');
Declare #WorkMin INT = 0 -- Initialize counter
Declare #Reverse BIT -- Flag to hold if direction is reverse
Declare #StartHour TIME = #BusinessDayStart -- Start of business hours (can be supplied as an argument if needed)
Declare #EndHour TIME = #BusinessDayEnd -- End of business hours (can be supplied as an argument if needed)
Declare #Holidays Table (HDate DateTime) -- Table variable to hold holidayes
-- If dates are in reverse order, switch them and set flag
If #StartDate>#EndDate
Begin
Declare #TempDate DateTime=#StartDate
Set #StartDate=#EndDate
Set #EndDate=#TempDate
Set #Reverse=1
End
Else Set #Reverse = 0
-- Get country holidays from table based on the country code (Feel free to remove this or modify as per your DB schema)
-- Insert Into #Holidays(HDate) select DATEADD(month,((LEFT(CAL_ID,4)-1900)*12)+LEFT(RIGHT(CAL_ID,4),2)-1,RIGHT(CAL_ID,2)-1) from B_CALENDAR where CAL_DAY_PK = 263 and HDATE >= DateAdd(dd, DateDiff(dd,0,#StartDate), 0)
Insert Into #Holidays (HDate) Select HolidayDate from V_BUS_HOL Where HolidayDate >= DateAdd(dd, DateDiff(dd,0,#StartDate), 0)
If CAST(#StartDate as TIME) < #StartHour Set #StartDate = CAST(CAST(#StartDate as DATE) as DATETIME) + CAST(#StartHour as DATETIME) -- If Start time is less than start hour, set it to start hour
If CAST(#StartDate as TIME) >= DATEADD(HOUR,1,#EndHour) Set #StartDate = CAST(CAST(DATEADD(DAY,1,#StartDate) as DATE) as DATETIME) + CAST(#StartHour as DATETIME) -- If Start time is after end hour, set it to start hour of next day
If CAST(#EndDate as TIME) >= DATEADD(HOUR,1,#EndHour) Set #EndDate = CAST(CAST(#EndDate as DATE) as DATETIME) + CAST(#EndHour as DATETIME) -- If End time is after end hour, set it to end hour
If CAST(#EndDate as TIME) < #StartHour Set #EndDate = CAST(CAST(DATEADD(DAY,-1,#EndDate) as DATE) as DATETIME) + CAST(#EndHour as DATETIME) -- If End time is before start hour, set it to end hour of previous day
If #StartDate>#EndDate Return 0
-- If Start and End is on same day
If DateDiff(Day,#StartDate,#EndDate) <= 0
Begin
If Datepart(dw,#StartDate)>1 And DATEPART(dw,#StartDate)<7 -- If day is between sunday and saturday
If (Select Count(*) From #Holidays Where HDATE=DateAdd(dd, DateDiff(dd,0,#StartDate), 0)) = 0 -- If day is not a holiday
If #EndDate<#StartDate Return 0 Else Set #WorkMin=DATEDIFF(SECOND, #StartDate, #EndDate) -- Calculate difference
Else Return 0
Else Return 0
End
Else Begin
Declare #Partial int=1 -- Set partial day flag
While DateDiff(Day,#StartDate,#EndDate) > 0 -- While start and end days are different
Begin
If Datepart(dw,#StartDate)>1 And DATEPART(dw,#StartDate)<7 -- If this is a weekday
Begin
If (Select Count(*) From #Holidays Where HDATE=DateAdd(dd, DateDiff(dd,0,#StartDate), 0)) = 0 -- If this is not a holiday
Begin
If #Partial=1 -- If this is the first iteration, calculate partial time
Begin
Set #WorkMin=#WorkMin + DATEDIFF(SECOND, #StartDate, DateAdd(hour, DATEPART(HOUR,#EndHour), DateDiff(DAY, 0, #StartDate)))
Set #StartDate=DateAdd(hour, DATEPART(HOUR,#StartHour)+24, DateDiff(DAY, 0, #StartDate))
Set #Partial=0
End
Else Begin -- If this is a full day, add full minutes
Set #WorkMin=#WorkMin + (DATEPART(HOUR,#EndHour)-DATEPART(HOUR,#StartHour))*60
Set #StartDate = DATEADD(DD,1,#StartDate)
End
End
Else Set #StartDate = DATEADD(DD,1,#StartDate)
End
Else Set #StartDate = DATEADD(DD,1,#StartDate)
End
If Datepart(dw,#StartDate)>1 And DATEPART(dw,#StartDate)<7 -- If last day is a weekday
If (Select Count(*) From #Holidays Where HDATE=DateAdd(dd, DateDiff(dd,0,#StartDate), 0)) = 0 -- And it is not a holiday
If #Partial=0 Set #WorkMin=#WorkMin + DATEDIFF(SECOND, #StartDate, #EndDate) Else Set #WorkMin=#WorkMin + DATEDIFF(SECOND, DateAdd(hour, DATEPART(HOUR,#StartHour), DateDiff(DAY, 0, #StartDate)), #EndDate)
End
If #Reverse=1 Set #WorkMin=-#WorkMin
Return #WorkMin
End

Answer 1

This one is an old one, however I believe that your problem is datetime/time data types. You didn't state the version of SQL Server you are using but if you have 2008 or above, you may want to adjust your tables and this function to use the datetime2 format. It is more accurate. datetime/smalldatetime both are only accurate to a certain point, then they round which could cause the problem you are looking at.