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

My version of the accepted answer as a function using DATEPART, so I don't have to do a string comparison on the line with

DATENAME(dw, @StartDate) = 'Sunday'

Anyway, here's my business datediff function

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE FUNCTION BDATEDIFF
(
    @startdate as DATETIME,
    @enddate as DATETIME
)
RETURNS INT
AS
BEGIN
    DECLARE @res int

SET @res = (DATEDIFF(dd, @startdate, @enddate) + 1)
    -(DATEDIFF(wk, @startdate, @enddate) * 2)
    -(CASE WHEN DATEPART(dw, @startdate) = 1 THEN 1 ELSE 0 END)
    -(CASE WHEN DATEPART(dw, @enddate) = 7 THEN 1 ELSE 0 END)

    RETURN @res
END
GO

Answer 2

For difference between dates including holidays I went this way:

1) Table with Holidays:

    CREATE TABLE [dbo].[Holiday](
[Id] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](50) NULL,
[Date] [datetime] NOT NULL)

2) I had my plannings Table like this and wanted to fill column Work_Days which was empty:

    CREATE TABLE [dbo].[Plan_Phase](
[Id] [int] IDENTITY(1,1) NOT NULL,
[Id_Plan] [int] NOT NULL,
[Id_Phase] [int] NOT NULL,
[Start_Date] [datetime] NULL,
[End_Date] [datetime] NULL,
[Work_Days] [int] NULL)

3) So in order to get "Work_Days" to later fill in my column just had to:

SELECT Start_Date, End_Date,
 (DATEDIFF(dd, Start_Date, End_Date) + 1)
-(DATEDIFF(wk, Start_Date, End_Date) * 2)
-(SELECT COUNT(*) From Holiday Where Date  >= Start_Date AND Date <= End_Date)
-(CASE WHEN DATENAME(dw, Start_Date) = 'Sunday' THEN 1 ELSE 0 END)
-(CASE WHEN DATENAME(dw, End_Date) = 'Saturday' THEN 1 ELSE 0 END)
-(CASE WHEN (SELECT COUNT(*) From Holiday Where Start_Date  = Date) > 0 THEN 1 ELSE 0 END)
-(CASE WHEN (SELECT COUNT(*) From Holiday Where End_Date  = Date) > 0 THEN 1 ELSE 0 END) AS Work_Days
from Plan_Phase

Hope that I could help.

Cheers

Answer 3

For workdays, Monday to Friday, you can do it with a single SELECT, like this:

DECLARE @StartDate DATETIME
DECLARE @EndDate DATETIME
SET @StartDate = '2008/10/01'
SET @EndDate = '2008/10/31'


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

If you want to include holidays, you have to work it out a bit...

Answer 4

(I'm a few points shy of commenting privileges)

If you decide to forgo the +1 day in CMS's elegant solution, note that if your start date and end date are in the same weekend, you get a negative answer. Ie., 2008/10/26 to 2008/10/26 returns -1.

my rather simplistic solution:

select @Result = (..CMS's answer..)
if  (@Result < 0)
        select @Result = 0
    RETURN @Result

.. which also sets all erroneous posts with start date after end date to zero. Something you may or may not be looking for.

Answer 5

DECLARE @StartDate datetime,@EndDate datetime

select @StartDate='3/2/2010', @EndDate='3/7/2010'

DECLARE @TotalDays INT,@WorkDays INT

DECLARE @ReducedDayswithEndDate INT

DECLARE @WeekPart INT

DECLARE @DatePart INT

SET @TotalDays= DATEDIFF(day, @StartDate, @EndDate) +1

SELECT @ReducedDayswithEndDate = CASE DATENAME(weekday, @EndDate)
    WHEN 'Saturday' THEN 1
    WHEN 'Sunday' THEN 2
    ELSE 0 END

SET @TotalDays=@TotalDays-@ReducedDayswithEndDate

SET @WeekPart=@TotalDays/7;

SET @DatePart=@TotalDays%7;

SET @WorkDays=(@WeekPart*5)+@DatePart

SELECT @WorkDays

Answer 6

If you need to add work days to a given date, you can create a function that depends on a calendar table, described below:

CREATE TABLE Calendar
(
  dt SMALLDATETIME PRIMARY KEY, 
  IsWorkDay BIT
);

--fill the rows with normal days, weekends and holidays.


create function AddWorkingDays (@initialDate smalldatetime, @numberOfDays int)
    returns smalldatetime as 

    begin
        declare @result smalldatetime
        set @result = 
        (
            select t.dt from
            (
                select dt, ROW_NUMBER() over (order by dt) as daysAhead from calendar 
                where dt > @initialDate
                and IsWorkDay = 1
                ) t
            where t.daysAhead = @numberOfDays
        )

        return @result
    end