Count work days between two dates

Question

How can I calculate the number of work days between two dates in SQL Server?

Monday to Friday and it must be T-SQL.

Answer 1

Create function like:

CREATE FUNCTION dbo.fn_WorkDays(@StartDate DATETIME, @EndDate DATETIME= NULL )
RETURNS INT 
AS
BEGIN
       DECLARE @Days int
       SET @Days = 0

       IF @EndDate = NULL
              SET @EndDate = EOMONTH(@StartDate) --last date of the month

       WHILE DATEDIFF(dd,@StartDate,@EndDate) >= 0
       BEGIN
              IF DATENAME(dw, @StartDate) <> 'Saturday' 
                     and DATENAME(dw, @StartDate) <> 'Sunday' 
                     and Not ((Day(@StartDate) = 1 And Month(@StartDate) = 1)) --New Year's Day.
                     and Not ((Day(@StartDate) = 4 And Month(@StartDate) = 7)) --Independence Day.
              BEGIN
                     SET @Days = @Days + 1
              END

              SET @StartDate = DATEADD(dd,1,@StartDate)
       END

       RETURN  @Days
END

You can call the function like:

select dbo.fn_WorkDays('1/1/2016', '9/25/2016')

Or like:

select dbo.fn_WorkDays(StartDate, EndDate) 
from table1

Answer 2

In Calculating Work Days you can find a good article about this subject, but as you can see it is not that advanced.

--Changing current database to the Master database allows function to be shared by everyone.
USE MASTER
GO
--If the function already exists, drop it.
IF EXISTS
(
    SELECT *
    FROM dbo.SYSOBJECTS
    WHERE ID = OBJECT_ID(N'[dbo].[fn_WorkDays]')
    AND XType IN (N'FN', N'IF', N'TF')
)
DROP FUNCTION [dbo].[fn_WorkDays]
GO
 CREATE FUNCTION dbo.fn_WorkDays
--Presets
--Define the input parameters (OK if reversed by mistake).
(
    @StartDate DATETIME,
    @EndDate   DATETIME = NULL --@EndDate replaced by @StartDate when DEFAULTed
)

--Define the output data type.
RETURNS INT

AS
--Calculate the RETURN of the function.
BEGIN
    --Declare local variables
    --Temporarily holds @EndDate during date reversal.
    DECLARE @Swap DATETIME

    --If the Start Date is null, return a NULL and exit.
    IF @StartDate IS NULL
        RETURN NULL

    --If the End Date is null, populate with Start Date value so will have two dates (required by DATEDIFF below).
     IF @EndDate IS NULL
        SELECT @EndDate = @StartDate

    --Strip the time element from both dates (just to be safe) by converting to whole days and back to a date.
    --Usually faster than CONVERT.
    --0 is a date (01/01/1900 00:00:00.000)
     SELECT @StartDate = DATEADD(dd,DATEDIFF(dd,0,@StartDate), 0),
            @EndDate   = DATEADD(dd,DATEDIFF(dd,0,@EndDate)  , 0)

    --If the inputs are in the wrong order, reverse them.
     IF @StartDate > @EndDate
        SELECT @Swap      = @EndDate,
               @EndDate   = @StartDate,
               @StartDate = @Swap

    --Calculate and return the number of workdays using the input parameters.
    --This is the meat of the function.
    --This is really just one formula with a couple of parts that are listed on separate lines for documentation purposes.
     RETURN (
        SELECT
        --Start with total number of days including weekends
        (DATEDIFF(dd,@StartDate, @EndDate)+1)
        --Subtact 2 days for each full weekend
        -(DATEDIFF(wk,@StartDate, @EndDate)*2)
        --If StartDate is a Sunday, Subtract 1
        -(CASE WHEN DATENAME(dw, @StartDate) = 'Sunday'
            THEN 1
            ELSE 0
        END)
        --If EndDate is a Saturday, Subtract 1
        -(CASE WHEN DATENAME(dw, @EndDate) = 'Saturday'
            THEN 1
            ELSE 0
        END)
        )
    END
GO

If you need to use a custom calendar, you might need to add some checks and some parameters. Hopefully it will provide a good starting point.

Answer 3

Create Function dbo.DateDiff_WeekDays 
(
@StartDate  DateTime,
@EndDate    DateTime
)
Returns Int
As

Begin   

Declare @Result Int = 0

While   @StartDate <= @EndDate
Begin 
    If DateName(DW, @StartDate) not in ('Saturday','Sunday')
        Begin
            Set @Result = @Result +1
        End
        Set @StartDate = DateAdd(Day, +1, @StartDate)
End

Return @Result

End

Answer 4

Here is a version that works well (I think). Holiday table contains Holiday_date columns that contains holidays your company observe.

DECLARE @RAWDAYS INT

   SELECT @RAWDAYS =  DATEDIFF(day, @StartDate, @EndDate )--+1
                    -( 2 * DATEDIFF( week, @StartDate, @EndDate ) )
                    + CASE WHEN DATENAME(dw, @StartDate) = 'Saturday' THEN 1 ELSE 0 END
                    - CASE WHEN DATENAME(dw, @EndDate) = 'Saturday' THEN 1 ELSE 0 END 

   SELECT  @RAWDAYS - COUNT(*) 
     FROM HOLIDAY NumberOfBusinessDays
    WHERE [Holiday_Date] BETWEEN @StartDate+1 AND @EndDate 

Answer 5

That's working for me, in my country on Saturday and Sunday are non-working days.

For me is important the time of @StartDate and @EndDate.

CREATE FUNCTION [dbo].[fnGetCountWorkingBusinessDays]
(
    @StartDate as DATETIME,
    @EndDate as DATETIME
)
RETURNS INT
AS
BEGIN
    DECLARE @res int

SET @StartDate = CASE 
    WHEN DATENAME(dw, @StartDate) = 'Saturday' THEN DATEADD(dd, 2, DATEDIFF(dd, 0, @StartDate))
    WHEN DATENAME(dw, @StartDate) = 'Sunday' THEN DATEADD(dd, 1, DATEDIFF(dd, 0, @StartDate))
    ELSE @StartDate END

SET @EndDate = CASE 
    WHEN DATENAME(dw, @EndDate) = 'Saturday' THEN DATEADD(dd, 0, DATEDIFF(dd, 0, @EndDate))
    WHEN DATENAME(dw, @EndDate) = 'Sunday' THEN DATEADD(dd, -1, DATEDIFF(dd, 0, @EndDate))
    ELSE @EndDate END


SET @res =
    (DATEDIFF(hour, @StartDate, @EndDate) / 24)
  - (DATEDIFF(wk, @StartDate, @EndDate) * 2)

SET @res = CASE WHEN @res < 0 THEN 0 ELSE @res END

    RETURN @res
END

GO

Answer 6

One approach is to 'walk the dates' from start to finish in conjunction with a case expression which checks if the day is not a Saturday or a Sunday and flagging it(1 for weekday, 0 for weekend). And in the end just sum flags(it would be equal to the count of 1-flags as the other flag is 0) to give you the number of weekdays.

You can use a GetNums(startNumber,endNumber) type of utility function which generates a series of numbers for 'looping' from start date to end date. Refer http://tsql.solidq.com/SourceCodes/GetNums.txt for an implementation. The logic can also be extended to cater for holidays(say if you have a holidays table)

declare @date1 as datetime = '19900101'
declare @date2 as datetime = '19900120'

select  sum(case when DATENAME(DW,currentDate) not in ('Saturday', 'Sunday') then 1 else 0 end) as noOfWorkDays
from dbo.GetNums(0,DATEDIFF(day,@date1, @date2)-1) as Num
cross apply (select DATEADD(day,n,@date1)) as Dates(currentDate)