Add business days to date in SQL without loops

Question

I currently have a function in my SQL database that adds a certain amount of business days to a date, e.g. if you enter a date that is a Thursday and add two days, it will r

Answer 1

I've very recently solved this problem to add two working days to the current date by creating an INT value @DaysToAdd - tested and working great on 2008 / 2012.

DECLARE @DaysToAdd INT

SELECT @DaysToAdd = CASE  
   WHEN DATEPART(WEEKDAY,GETDATE()) =  1 THEN 3 -- Sunday -> Wednesday
   WHEN DATEPART(WEEKDAY,GETDATE()) =  5 THEN 4 -- Thursday -> Monday
   WHEN DATEPART(WEEKDAY,GETDATE()) =  6 THEN 4 -- Friday -> Tuesday
   WHEN DATEPART(WEEKDAY,GETDATE()) =  7 THEN 4 -- Saturday -> Wednesday
   ELSE 2 END

SELECT DATEADD(DAY, @DaysToAdd, GETDATE()) AS TwoWorkingDaysTime

Answer 2

I found a much more elegant approach from Microsoft Docs. It takes into account skipping multiple weekends. Super clean.

CREATE FUNCTION DAYSADDNOWK(@addDate AS DATE, @numDays AS INT)
RETURNS DATETIME
AS
BEGIN
    WHILE @numDays>0
    BEGIN
       SET @addDate=DATEADD(d,1,@addDate)
       IF DATENAME(DW,@addDate)='saturday' SET @addDate=DATEADD(d,1,@addDate)
       IF DATENAME(DW,@addDate)='sunday' SET @addDate=DATEADD(d,1,@addDate)

       SET @numDays=@numDays-1
    END

    RETURN CAST(@addDate AS DATETIME)
END
GO

Run the test

SELECT dbo.DAYSADDNOWK(GETDATE(), 15)

Answer 3

This is better if anyone is looking for a TSQL solution. No loops, no tables, no case statements AND works with negatives. Can anyone beat that?

CREATE FUNCTION[dbo].[AddBusinessDays](@Date date,@n INT)
RETURNS DATE AS 
BEGIN
DECLARE @d INT;SET @d=4-SIGN(@n)*(4-DATEPART(DW,@Date));
RETURN DATEADD(D,@n+((ABS(@n)+@d-2)/5)*2*SIGN(@n)-@d/7,@Date);
END

Answer 4

Building off of the answer that was accepted for this question, the following user-defined function (UDF) should work in all cases--regardless of the setting for @@DateFirst.

UPDATE: As comments below indicate, this function is designed for the FromDate to be a weekday. The behavior is undefined when a weekend day is passed in as the FromDate.

ALTER FUNCTION [dbo].[BusinessDaysDateAdd] 
(
   @FromDate datetime,
   @DaysToAdd int
)
RETURNS datetime
AS
BEGIN
   DECLARE @Result datetime

   SET @Result = DATEADD(day, (@DaysToAdd % 5) + CASE ((@@DATEFIRST + DATEPART(weekday, @FromDate) + (@DaysToAdd % 5)) % 7)
                                                 WHEN 0 THEN 2
                                                 WHEN 1 THEN 1
                                                 ELSE 0 END, DATEADD(week, (@DaysToAdd / 5), @FromDate))

   RETURN @Result
END

Answer 5

This is an old thread but I just created a table with all the dates then did this:

SELECT Count(*) 
FROM Date_Table
WHERE [day] BETWEEN @StartDate and @EndDate
    AND DATENAME(weekday, [day]) NOT IN ('Sunday', 'Saturday')

Answer 6

I know it's a little bit late, perhaps someone else stumble upon this problem. I've tried the above solution but, most of them can't calculate holidays.

This is how i tried

CREATE function [dbo].[DateAddWorkDay]
(@days int,@FromDate Date)
returns Date
as
begin
declare @result date
set @result = (
select b
from
(
    SELECT
    b,
       (DATEDIFF(dd, a, b))
      -(DATEDIFF(wk, a, b) * 2)
      -(CASE WHEN DATENAME(dw, a) = 'Sunday' THEN 1 ELSE 0 END)
      -(CASE WHEN DATENAME(dw, b) = 'Saturday' THEN 1 ELSE 0 END)
      -COUNT(o.Holiday_Date) 
      as workday
    from
    (
    select 
    @FromDate as a,
    dateadd(DAY,num +@days,@FromDate) as b
    from (select row_number() over (order by (select NULL)) as num
          from Information_Schema.columns
         ) t
    where num <= 100 
    ) dt
    left join Holiday o on o.Holiday_Date between a and b and DATENAME(dw, o.Holiday_Date) not in('Saturday','Sunday') 
    where DATENAME(dw, b) not in('Saturday','Sunday')
          and b not in (select Holiday_Date from OP_Holiday where Holiday_Date between a and b) 

    group by a,b
) du
where workday =@days 


)
return @result 
end

Where Holiday is a table with holiday_date as a reference for holiday

Hope this can help some one.