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

All Credit to Bogdan Maxim & Peter Mortensen. This is their post, I just added holidays to the function (This assumes you have a table "tblHolidays" with a datetime field "HolDate".

--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)
        --Subtract all holidays
        -(Select Count(*) from [DB04\DB04].[Gateway].[dbo].[tblHolidays]
          where  [HolDate] between @StartDate and @EndDate )
        )
    END  
GO
-- Test Script
/*
declare @EndDate datetime= dateadd(m,2,getdate())
print @EndDate
select  [Master].[dbo].[fn_WorkDays] (getdate(), @EndDate)
*/

Answer 2

(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 3

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 4

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 5

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 6

I borrowed some ideas from others to create my solution. I use inline code to ignore weekends and U.S. federal holidays. In my environment, EndDate may be null, but it will never precede StartDate.

CREATE FUNCTION dbo.ufn_CalculateBusinessDays(
@StartDate DATE,
@EndDate DATE = NULL)

RETURNS INT
AS

BEGIN
DECLARE @TotalBusinessDays INT = 0;
DECLARE @TestDate DATE = @StartDate;


IF @EndDate IS NULL
    RETURN NULL;

WHILE @TestDate < @EndDate
BEGIN
    DECLARE @Month INT = DATEPART(MM, @TestDate);
    DECLARE @Day INT = DATEPART(DD, @TestDate);
    DECLARE @DayOfWeek INT = DATEPART(WEEKDAY, @TestDate) - 1; --Monday = 1, Tuesday = 2, etc.
    DECLARE @DayOccurrence INT = (@Day - 1) / 7 + 1; --Nth day of month (3rd Monday, for example)

    --Increment business day counter if not a weekend or holiday
    SELECT @TotalBusinessDays += (
        SELECT CASE
            --Saturday OR Sunday
            WHEN @DayOfWeek IN (6,7) THEN 0
            --New Year's Day
            WHEN @Month = 1 AND @Day = 1 THEN 0
            --MLK Jr. Day
            WHEN @Month = 1 AND @DayOfWeek = 1 AND @DayOccurrence = 3 THEN 0
            --G. Washington's Birthday
            WHEN @Month = 2 AND @DayOfWeek = 1 AND @DayOccurrence = 3 THEN 0
            --Memorial Day
            WHEN @Month = 5 AND @DayOfWeek = 1 AND @Day BETWEEN 25 AND 31 THEN 0
            --Independence Day
            WHEN @Month = 7 AND @Day = 4 THEN 0
            --Labor Day
            WHEN @Month = 9 AND @DayOfWeek = 1 AND @DayOccurrence = 1 THEN 0
            --Columbus Day
            WHEN @Month = 10 AND @DayOfWeek = 1 AND @DayOccurrence = 2 THEN 0
            --Veterans Day
            WHEN @Month = 11 AND @Day = 11 THEN 0
            --Thanksgiving
            WHEN @Month = 11 AND @DayOfWeek = 4 AND @DayOccurrence = 4 THEN 0
            --Christmas
            WHEN @Month = 12 AND @Day = 25 THEN 0
            ELSE 1
            END AS Result);

    SET @TestDate = DATEADD(dd, 1, @TestDate);
END

RETURN @TotalBusinessDays;
END