Related
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 return the date of the following Monday. I'm not bothered about any holidays, only weekends are excluded.
The problem is that this is currently done using a while loop, and it appears to be massively slowing down the stored procedure that uses it while generating a table. Does anyone know if there is any way to perform this calculation without while loops or cursors?
Just for information, this is the current function:
ALTER FUNCTION [dbo].[AddWorkDaysToDate]
(
#fromDate datetime,
#daysToAdd int
)
RETURNS datetime
AS
BEGIN
DECLARE #toDate datetime
DECLARE #daysAdded integer
-- add the days, ignoring weekends (i.e. add working days)
set #daysAdded = 1
set #toDate = #fromDate
while #daysAdded <= #daysToAdd
begin
-- add a day to the to date
set #toDate = DateAdd(day, 1, #toDate)
-- only move on a day if we've hit a week day
if (DatePart(dw, #toDate) != 1) and (DatePart(dw, #toDate) != 7)
begin
set #daysAdded = #daysAdded + 1
end
end
RETURN #toDate
END
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
This answer has been significantly altered since it was accepted, since the original was wrong. I'm more confident in the new query though, and it doesn't depend on DATEFIRST
I think this should cover it:
declare #fromDate datetime
declare #daysToAdd int
select #fromDate = '20130123',#DaysToAdd = 4
declare #Saturday int
select #Saturday = DATEPART(weekday,'20130126')
;with Numbers as (
select 0 as n union all select 1 union all select 2 union all select 3 union all select 4
), Split as (
select #DaysToAdd%5 as PartialDays,#DaysToAdd/5 as WeeksToAdd
), WeekendCheck as (
select WeeksToAdd,PartialDays,MAX(CASE WHEN DATEPART(weekday,DATEADD(day,n.n,#fromDate))=#Saturday THEN 1 ELSE 0 END) as HitWeekend
from
Split t
left join
Numbers n
on
t.PartialDays >= n.n
group by WeeksToAdd,PartialDays
)
select DATEADD(day,WeeksToAdd*7+PartialDays+CASE WHEN HitWeekend=1 THEN 2 ELSE 0 END,#fromDate)
from WeekendCheck
We split the time to be added into a number of weeks and a number of days within a week. We then use a small numbers table to work out if adding those few days will result in us hitting a Saturday. If it does, then we need to add 2 more days onto the total.
This answers is based on #ElmerMiller's answer.
It fixes the negative value on Sunday comment from #FistOfFury
Negative values don't work if the date passed in is Sunday
And the DATEFIRST setting comment from #Damien_The_Unbeliever
But this one does assume a particular DATEFIRST setting (7), which some of the others don't need.
Now the corrected function
CREATE FUNCTION[dbo].[AddBusinessDays](#Date DATE,#n INT)
RETURNS DATE AS
BEGIN
DECLARE #d INT,#f INT,#DW INT;
SET #f=CAST(abs(1^SIGN(DATEPART(DW, #Date)-(7-##DATEFIRST))) AS BIT)
SET #DW=DATEPART(DW,#Date)-(7-##DATEFIRST)*(#f^1)+##DATEFIRST*(#f&1)
SET #d=4-SIGN(#n)*(4-#DW);
RETURN DATEADD(D,#n+((ABS(#n)+(#d%(8+SIGN(#n)))-2)/5)*2*SIGN(#n)-#d/7,#Date);
END
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
Have you thought about pre-populating a look-up table that contains all of the working days (using your function) , for example WorkingDays(int DaySequenceId, Date WorkingDate), you can then use this table by selecting the DaySequenceId of the #fromDate and add #daysToAdd to get the new working date. Obviously this method also has the additional overhead of administering the WorkingDays table, but you could pre-populate it with the range of dates you expect. The other downside is the working dates that can be calculated will only be those contained within the WorkingDays table.
To expand on Amine's comment and Nate cook's answer above, the one-liner solution to this is:
declare #DaysToAdd int , #FromDate datetime
set #DaysToAdd=-5 --5 days prior is 3/28/14
set #FromDate='4/4/14'
select
DATEADD(day, (#DaysToAdd % 5)
+ CASE
WHEN ((##DATEFIRST + DATEPART(weekday, #FromDate)) % 7 + (#DaysToAdd % 5)) > 6 THEN 2
ELSE 0
END
, DATEADD(week, (#DaysToAdd / 5), #FromDate))
Note you can add or subtract days to go forwards and backwards in time, respectively.
*I know this is an old thread but found something extremely useful a while ago, modified it and got this.
select ((DATEADD(d,DATEDIFF(d,0,(DATEADD (d,2,#fromDate))),#numbOfDays)))*
Update: I am sorry in a haste to find a piece of code (in a single statement) and to avoid using a function, I posted incorrect code here.
Bit mentioned above can be used if the number of days you are adding is 7 or less.
I have changed the code with required parameters for better understanding.
Anyway, I ended up using what 'Nate Cook' has mentioned above. And used it as a single line of code. (Because I am restraining from using functions)
Nate's code
select(
DATEADD(day, (#days % 5) +
CASE ((##DATEFIRST + DATEPART(weekday, GETDATE()) + (#days % 5)) % 7)
WHEN 0 THEN 2
WHEN 1 THEN 1
ELSE 0 END, DATEADD(week, (#days / 5), GETDATE()))
)
I have tested all of the solutions proposed here and none of them work.
Here are some test scenarios that broke a lot of the above solutions.
(assuming Saturday and Sunday are the days you are excluding):
-Add 0 days to a Saturday - Expected result = Saturday
-Add 0 days to a Sunday - Expected result = Sunday
-Add 1 day to Friday - Expected result = the following Monday
-Add 1 day to Saturday - Expected result = the following Monday
-Add 1 day to Sunday - Expected result = the following Monday
-Add 3 days to Friday - Expected result = the following Wednesday
-Add 5 days to Saturday - Expected result = the following Friday
-Add 5 days to Friday - Expected result = the following Friday
-Subtract 1 day from Monday - Expected result = the previous Friday
-Subtract 1 day from Sunday - Expected result = the previous Friday
-Subtract 1 day from Saturday - Expected result = the previous Friday
-Subtract 3 days from Monday - Expected result = the previous Wednesday
-Subtract 5 days from Saturday - Expected result = the previous Monday
-Subtract 5 days from Monday - Expected result = the previous Monday
Here is what I wrote after reading this entire thread and picking the good pieces of logic:
CREATE FUNCTION [dbo].[BusinessDateAdd]
(
#FromDate DATE
,#DaysToAdd INT
)
RETURNS DATE
AS
BEGIN
--If there are no days to add or subtract, return the day that was passed in
IF #DaysToAdd = 0 RETURN #FromDate
DECLARE #Weeks INT
DECLARE #DMod INT
DECLARE #FromDateIndex INT
--number of weeks
SET #Weeks = #DaysToAdd/5
--remainder of days
SET #dmod = #DaysToAdd%5
--Get the FromDate day of the week, this logic standardizes the ##DateFirst to Sunday = 1
SET #FromDateIndex = (DATEPART(weekday, #FromDate) + ##DATEFIRST - 1) % 7 + 1
/*Splitting the addition vs subtraction logic for readability*/
--Adding business days
IF #DaysToAdd > 0
BEGIN
--If the FromDate is on a weekend, move it to the previous Friday
IF #FromDateIndex IN(1,7)
BEGIN
SET #FromDate = DATEADD(dd,CASE #FromDateIndex WHEN 1 THEN -2 WHEN 7 THEN -1 END,#FromDate)
SET #FromDateIndex = 6
END
SET #FromDate = DATEADD(dd,
CASE
--If the mod goes through the weekend, add 2 days to account for it
WHEN
((#FromDateIndex = 3 --Tuesday
AND #dmod > 3) --Days until Friday
OR
(#FromDateIndex = 4 --Wednesday
AND #dmod > 2)--Days until Friday
OR
(#FromDateIndex = 5 --Thursday
AND #dmod > 1)--Days until Friday
OR
(#FromDateIndex = 6 --Friday
AND #dmod > 0))--Days until Friday
THEN
#DMod+2
--Otherwise just add the mod
ELSE
#DMod
END, #FromDate)
END
--Subtracting business days
IF #DaysToAdd < 0
BEGIN
--If the FromDate is on a weekend, move it to the next Monday
IF #FromDateIndex IN(1,7)
BEGIN
SET #FromDate = DATEADD(dd,CASE #FromDateIndex WHEN 1 THEN 1 WHEN 7 THEN 2 END,#FromDate)
SET #FromDateIndex = 2
END
SET #FromDate = DATEADD(dd,
CASE
--If the mod goes through the weekend, subtract 2 days to account for it
WHEN
((#FromDateIndex = 5 --Thursday
AND #dmod < -3) --Days until Monday
OR
(#FromDateIndex = 4 --Wednesday
AND #dmod < -2)--Days until Monday
OR
(#FromDateIndex = 3 --Tuesday
AND #dmod < -1)--Days until Monday
OR
(#FromDateIndex = 2 --Monday
AND #dmod < 0))--Days until Monday
THEN
#DMod-2
--Otherwise just subtract the mod
ELSE
#DMod
END, #FromDate)
END
--Shift the date by the number of weeks
SET #FromDate = DATEADD(ww,#Weeks,#FromDate)
RETURN #FromDate
END
CREATE FUNCTION DateAddBusinessDays
(
#Days int,
#Date datetime
)
RETURNS datetime
AS
BEGIN
DECLARE #DayOfWeek int;
SET #DayOfWeek = CASE
WHEN #Days < 0 THEN (##DateFirst + DATEPART(weekday, #Date) - 20) % 7
ELSE (##DateFirst + DATEPART(weekday, #Date) - 2) % 7
END;
IF #DayOfWeek = 6 SET #Days = #Days - 1
ELSE IF #DayOfWeek = -6 SET #Days = #Days + 1;
RETURN #Date + #Days + (#Days + #DayOfWeek) / 5 * 2;
END;
This function can add and subtract business days regardless of the value of ##DATEFIRST. To subtract business days use a negative number of days.
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)
I don't have Sql Server at the moment to test but this is the idea:
ALTER FUNCTION [dbo].[AddWorkDaysToDate]
(
#fromDate datetime,
#daysToAdd int
)
RETURNS datetime
AS
BEGIN
DECLARE #dw integer
DECLARE #toDate datetime
set datefirst 1
set #toDate = dateadd(day, #daysToAdd, #fromDate)
set #dw = datepart(dw, #toDate)
if #dw > 5 set #toDate = dateadd(day, 8 - #dw, #toDate)
RETURN #toDate
END
Thanks Damien for the code. There was a slight error in the calcs in that it added only 1 day for the sunday, and that when the number of business days crossed a weekend (but did not land in the weekend) the extra 2 days was not taken into account. Here is a modified version of Damiens code that works with the default datefirst at 7. Hope this helps.
CREATE FUNCTION [dbo].[fn_AddBusinessDays]
(
#StartDate datetime,
#BusinessDays int
)
RETURNS datetime
AS
BEGIN
DECLARE #EndDate datetime
SET #EndDate = DATEADD(day, #BusinessDays%5 +
CASE
WHEN DATEPART(weekday,#StartDate) + #BusinessDays%5 > 6 THEN 2
ELSE 0
END,
DATEADD(week,#BusinessDays/5,#StartDate))
RETURN #EndDate
END
GO
The question's accepted answer produces incorrect results. E.g. select #fromDate = '03-11-1983', #DaysToAdd = 3 results in 03-14-1983 while 03-16-1983 is expected.
I posted a working solution here, but for completeness sake I will also add it here. If you are interested in the details of the two methods go visit my original answer. If not, simply copy/pasta this into your SQL project and use UTL_DateAddWorkingDays
Note that my solution only works if DATEFIRST is set to the default value of 7.
Test Script used to test various methods
CREATE FUNCTION [dbo].[UTL_DateAddWorkingDays]
(
#date datetime,
#days int
)
RETURNS TABLE AS RETURN
(
SELECT
CASE
WHEN #days = 0 THEN #date
WHEN DATEPART(dw, #date) = 1 THEN (SELECT Date FROM [dbo].[UTL_DateAddWorkingDays_Inner](DATEADD(d, 1, #date), #days - 1))
WHEN DATEPART(dw, #date) = 7 THEN (SELECT Date FROM [dbo].[UTL_DateAddWorkingDays_Inner](DATEADD(d, 2, #date), #days - 1))
ELSE (SELECT Date FROM [dbo].[UTL_DateAddWorkingDays_Inner](#date, #days))
END AS Date
)
CREATE FUNCTION [dbo].[UTL_DateAddWorkingDays_Inner]
(
#date datetime,
#days int
)
RETURNS TABLE AS RETURN
(
SELECT
DATEADD(d
, (#days / 5) * 7
+ (#days % 5)
+ (CASE WHEN ((#days%5) + DATEPART(dw, #date)) IN (1,7,8,9,10) THEN 2 ELSE 0 END)
, #date) AS Date
)
This is what I use:
SET DATEFIRST 1;
SELECT DATEADD(dw, (**NumberToAdd**/5)*7+(**NumberToAdd** % 5) +
(CASE WHEN DATEPART(dw,**YourDate**) + (**NumberToAdd** % 5) > 5
THEN 2 ELSE 0 END), **YourDate**) AS IncrementedDate
FROM YourTable t
The "SET DATEFIRST 1;" part is necessary to set Monday as the first day of the week.
WITH get_dates
AS
(
SELECT getdate() AS date, 0 as DayNo
UNION ALL
SELECT date + 1 AS date, case when DATEPART(DW, date + 1) IN (1,7) then DayNo else DayNo + 1 end
FROM get_dates
WHERE DayNo < 4
)
SELECT max(date) FROM get_dates
OPTION (MAXRECURSION 0)
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')
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.
This SQL function works similar to Excel WORKDAY function.
Hope it can help you.
CREATE FUNCTION [dbo].[BusDaysDateAdd]
(
#FromDate date,
#DaysToAdd int
)
RETURNS date
AS
BEGIN
DECLARE #Result date
DECLARE #TempDate date
DECLARE #Remainder int
DECLARE #datePartValue int
SET #TempDate = (DATEADD(week, (#DaysToAdd / 5), #FromDate))
SET #Remainder = (#DaysToAdd % 5)
SET #datePartValue = DATEPART(weekday, #TempDate)
SET #Result = DATEADD(day,#Remainder + CASE WHEN #Remainder > 0 AND #datePartValue = 7 THEN 1
WHEN #Remainder >= 1 AND #datePartValue = 6 THEN 2
WHEN #Remainder >= 2 AND #datePartValue = 5 THEN 2
WHEN #Remainder >= 3 AND #datePartValue = 4 THEN 2
WHEN #Remainder >= 4 AND #datePartValue = 3 THEN 2
WHEN #Remainder >= 5 AND #datePartValue = 2 THEN 2
ELSE 0 END, #TempDate)
RETURN #Result
END
GO
Reference
I'm a little late to this party but I wound up writing my own version of this, because of drawbacks in the other solutions. Specifically this version addresses counting backwards, and starting on weekends.
There's an ambiguous situation that could arise, if you add zero business days to a weekend date. I've kept the date the same, but you can leave out this check if you always want to force a weekday to be returned.
CREATE FUNCTION [dbo].[fn_AddBusinessDays]
(
#date datetime,
#businessDays int
)
RETURNS datetime
AS
BEGIN
--adjust for weeks first
declare #weeksToAdd int = #businessDays / 7
declare #daysToAdd int = #businessDays % 7
--if subtracting days, subtract a week then offset
if #businessDays < 0 begin
set #daysToAdd = #businessDays + 5
set #weeksToAdd = #weeksToAdd - 1
end
--saturday becomes zero using the modulo operator
declare #originalDayOfWeek int = datepart(dw, #date) % 7
declare #newDayOfWeek int = datepart(dw, dateadd(d, #daysToAdd, #date)) % 7
--special case for when beginning date is weekend
--adding zero on a weekend keeps the same date. you can remove the <> 0 check if you want Sunday + 0 => Monday
declare #dateOffset int = case
when #businessDays <> 0 and #originalDayOfWeek = 0 then 2
when #businessDays <> 0 and #originalDayOfWeek = 1 then 1
when #businessDays <> 0 and #newDayOfWeek < #originalDayOfWeek then 2
else 0
end
-- Return the result of the function
return dateadd(d, #daysToAdd + #dateOffset, dateadd(ww, #weeksToAdd, #date))
END
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
I just tested the accepted answer and found that it does not work when Sunday is the start day.
You need to add the following under the Select #Saturday line item:
SELECT #fromDate = CASE WHEN DATEPART(weekday,#fromDate) = 1 THEN DATEADD(day,1,#fromDate) ELSE #fromDate END
Sigh. I can't believe after all these decades there's still no : a) standard "DateAddWorkDays" in Microsoft SQL Server (even though Microsoft has had a WorkDay Function in Excel forever) and b) clear solution in here or anywhere else I can find that handles all issues people have raised.
Here's a solution I developed that addresses the following issues that seemingly all the above answers here and elsewhere I've been able to find has one or more of. This handles:
Mnemonic identifier names.
Comments explaining code that's not clear.
Not checking every single work day needing to be incremented (i.e.
much less than O(n) complexity).
Negative work day increments.
Allowing non-12 am time portion to be passed in (so you won't have to strip it first).
Retaining the passed-in time portion, if any, in the result (in case you need the exact time x-business days ahead/ago).
Weekend day names in languages other than English.
##DateFirst values other than the default (7 aka U.S.).
Specifying a custom list of non-weekend non-working days.
Allowing list of non-weekend non-working days to work if passed-in date has a non-12 am time.
Returning starting date-time if # work days increment is 0 even if starting date-time is on a non-working day.
Moving to the next / previous working day first before starting to increment / decrement working days, respectively. NOTE: This differs from Excel's WorkDay Function, but I believe this is more useful and intuitive. Ex. If you get an inquiry / order on a weekend day, and you have an SLA (i.e. response time, delivery date) of 1 business day, you shouldn't have to respond / deliver until 1 full working day has passed (regardless of how many adjacent non-working days preceeded it).
Skipping any additional weekends and/or non-working weekdays that may have been spanned after adding any non-working weekdays back in that may have been spanned when adding initial weekends spanned when adding # of working days alone - and repeating until no longer necessary.
SUGGESTIONS: Of course, as with any recursive algorithm, this one can be converted to an iterative one (by implementing your own stack, i.e. with a Temp Table), but I think the 32 nesting levels is way more than enough for the vast majority of real-world use cases. Also, of course, you can make it more generic / portable by passing in the non-working weekday dates as a Table-Valued Parameter vs. a hard-coded Table reference.
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- ===================================================================================================================================
-- Author: Tom
-- Create date: 03/13/2017
-- Description: Add specified # of working days (+/-) to a specified date-time assuming existence of a list of non-work weekday
-- dates (incl. holidays, weather days, utility outage days, fire days, etc.) in the 'NonWorkDayDate' Column of a 'NonWorkWeekday'
-- Table. If specified # working days is 0, the specified date-time is returned. Working days are not added until the specified
-- date-time has first been incremented (+/-) to the next working day in the direction of the working days increment.
-- NOTE: Uses a forumla (vs. O(n) loop) that uses recusion whenever days incremented (incl. weekends) spans non-work weekdays.
-- !!!WARNING!!!: Will exceed SQL Server nesting level (32) if abs (# of working days) < ~1 / 32 adjacent non-working days.
-- Parameters:
-- #RefDateTime DateTime: Reference date-time to which to add '#WorkDaysIncrement'.
-- #WorkDaysIncrement Int: # of working days (+/-) to add # to the '#RefDateTime'.
-- Returns:
-- 1. Result of #RefDateTime + #WorkDaysIncrement (skipping weekend and holiday dates and retaining the #RefDateTime's time).
-- ===================================================================================================================================
CREATE FUNCTION [dbo].[AddWorkDays_Recursive]
(
-- Add the parameters for the function here
#RefDateTime datetime,
#WorkDaysIncrement int
)
RETURNS DateTime
AS
BEGIN
-- If no days to increment, return passed in date-time (even if weekend day).
if (#WorkDaysIncrement = 0) return #RefDateTime
-- Set the one-day increment used to add or subtract one calendar/work day.
declare #OneDayIncrement int = sign(#WorkDaysIncrement)
-- Initialize # of calendar days added to 0.
declare #DaysAdded int = 0
-- Set reference date to date (i.e. excl. time) of reference date-time.
declare #RefDate datetime = convert
(
date,
convert
(
varchar(10),
#RefDateTime,
101
)
)
--end declare #RefDate
-- Initialize result date to reference date
declare #ResultDate datetime = #RefDate
-- Set U.S. Weekday # to the 1-based U.S. weekday # result date.
declare #USWeekdayNumber tinyint = ((datepart(weekday, #ResultDate) + ##datefirst - 1) % 7) + 1 -- Sun to Sat = 1 to 7
-- If result date is now on a weekend day, set # of weekend days increment so that we can move it +/- 1 to 2 days to next weekday.
declare #WeekendDaysInc smallint =
(
case (#USWeekdayNumber)
when 1 then --Sunday
case
when (#OneDayIncrement > 0) then 1
else -2
end
--end when 1 --Sunday
when 7 then --Saturday
case
when (#OneDayIncrement > 0) then 2
else -1
end
--end when 7 then --Saturday
else 0 -- Not Weekend Day #
end -- case (#USWeekdayNumber)
) -- end declare #WeekendDaysInc smallint =
-- Increment # of calendar days added by # of weekend days increment
set #DaysAdded += #WeekendDaysInc
-- Increment result date by # of weekend days increment
set #ResultDate += #WeekendDaysInc
-- Set # of work weeks increment to # of full 5-day increments in the # (+/-) of work days to increment.
declare #WorkWeeksIncrement int = #WorkDaysIncrement / 5
-- Increment # of calendar days added by 7 times # of work weeks increment, i.e. to add weekday + weekend days for full weeks.
set #DaysAdded += #WorkWeeksIncrement * 7
-- Set result date after full weeks added to reference date + # of calendar days
declare #AfterFullWeeksResultDate datetime = #ResultDate + #DaysAdded
-- Set # partial-work week days to # (+/-) of work days to increment left after adding full weeks.
declare #PartialWorkWeekDays int = #WorkDaysIncrement % 5
-- Increment # of calendar days added by # partial-work week days
set #DaysAdded += #PartialWorkWeekDays
-- Set result date after partial week added to result date after full weeks added + # partial work week days
declare #AfterPartialWeekResultDate datetime = #AfterFullWeeksResultDate + #PartialWorkWeekDays
--Set result date to result date after partial week.
set #ResultDate = #AfterPartialWeekResultDate
-- Set After Full Weeks U.S. Weekday # to the 1-based U.S. weekday # result date.
declare #AfterFullWeeksUSWeekdayNumber tinyint =
(
((datepart(weekday, #AfterFullWeeksResultDate) + ##datefirst - 1) % 7) + 1 -- Sun to Sat = 1 to 7
)
-- Set After Partial Week U.S. Weekday # to the 1-based U.S. weekday # result date.
declare #AfterPartialWeekUSWeekdayNumber tinyint =
(
((datepart(weekday, #AfterPartialWeekResultDate) + ##datefirst - 1) % 7) + 1 -- Sun to Sat = 1 to 7
)
--If (incrementing and After Full Weeks U.S. Weekday # > #AfterPartialWeekUSWeekdayNumber)
-- or (decrementing and After Full Weeks U.S. Weekday # < #AfterPartialWeekUSWeekdayNumber), increment by (+/-) 2 to account for
-- the weekend that was spanned when partial-work week days were added.
if
(
(
(#OneDayIncrement > 0)
and (#AfterFullWeeksUSWeekdayNumber > #AfterPartialWeekUSWeekdayNumber)
)
or (
(#OneDayIncrement < 0)
and (#AfterFullWeeksUSWeekdayNumber < #AfterPartialWeekUSWeekdayNumber)
)
)
begin
set #WeekendDaysInc = 2 * #OneDayIncrement
set #DaysAdded += #WeekendDaysInc
set #ResultDate += #WeekendDaysInc
end -- if need to increment to account for weekend spanned by partial-work week days,
-- Set U.S. Weekday # to the 1-based U.S. weekday # result date.
set #USWeekdayNumber = ((datepart(weekday, #ResultDate) + ##datefirst - 1) % 7) + 1 -- Sun to Sat = 1 to 7
-- If result date is now on a weekend day, set # of weekend days increment so that we can move it +/- 1 to 2 days to next weekday.
set #WeekendDaysInc =
(
case (#USWeekdayNumber)
when 1 then --Sunday
case
when (#OneDayIncrement > 0) then 1
else -2
end
--end when 1 --Sunday
when 7 then --Saturday
case
when (#OneDayIncrement > 0) then 2
else -1
end
--end when 7 then --Saturday
else 0 -- Not Weekend Day #
end -- case (#USWeekdayNumber)
) -- end declare #WeekendDaysInc smallint =
-- Increment # of calendar days added by # of weekend days increment
set #DaysAdded += #WeekendDaysInc
-- Increment result date by # of weekend days increment
set #ResultDate += #WeekendDaysInc
-- Set non-work weedays count to # Rows where NonWorkDayDate between RefDate and ResultDate (if # of work days to increment > 0), else between
-- ResultDate and RefDate.
declare #NonWorkWeekdaysCount int =
(
select count(nw.NonWorkDayDate)
from NonWorkWeekday as nw
where
(
(#OneDayIncrement > 0)
and (nw.NonWorkDayDate between #RefDate and #ResultDate)
)
or (
(#OneDayIncrement < 0)
and (nw.NonWorkDayDate between #ResultDate and #RefDate)
)
--end select count(nw.NonWorkDayDate) from Holidate as nw
) -- end declare #HolidaysSpanned int =
-- Set result date-time to reference date-time + # of calendar days added
declare #ResultDateTime datetime = #RefDateTime + #DaysAdded
-- Set result date-time equal to result of adding (# of holidays x one-day increment).
set #ResultDateTime = dbo.AddWorkDays_Recursive
(
#ResultDateTime, -- #RefDateTime
#NonWorkWeekdaysCount * #OneDayIncrement -- #WorkDaysIncrement
)
--end set #ResultDateTime =
-- Return the result of the function
RETURN #ResultDateTime
END
GO
For Germany all of the answers don't work.
The only function I tested and works is a translation from an old Excel form here:
Set #EndDate=Dateadd(DAY,#DaysToAdd,#FromDate) +
Cast(((
CASE WHEN 5 <= DATEPART(weekday, #FromDate)%7
THEN 5
ELSE
DATEPART(weekday, #FromDate)%7
END)
-1 + #DaysToAdd )/5
as int)
* 2 -
(Case when DAtepart(weekday, #FromDate)=6 then 1 else 0 end)
--Refactoring my original answer... I've added the option to define the starting point of the calculation if the starting date happens to be a weekend day: start from that weekend day or shift to the nearest weekday depending on the direction of the delta.
DECLARE
#input DATE = '2019-06-15', -- if null, then returns null
#delta INT = 1, -- can be positive or negative; null => zero
#startFromWeekend BIT = 1 -- null => zero
-- input is null, delta is zero/null
IF #input IS NULL OR ISNULL(#delta, 0) = 0
SELECT #input
-- input is not null and has delta
ELSE
BEGIN
DECLARE
#input_dw INT = (DATEPART(DW, #input) + ##DATEFIRST - 1) % 7, -- input day of week
#weeks INT = #delta / 5, -- adjust by weeks
#days INT = #delta % 5 -- adjust by days
-- if input is a weekend day, offset it for proper calculation
-- !!important!!: depends on *your* definition of the starting date to perform calculation from
DECLARE #offset INT =
-- start calc from weekend day that is nearest to a weekday depending on delta direction
-- pos delta: effectively Sunday of the weekend (actual: prev Friday)
-- neg delta: effectively Saturday of the weekend (actual: next Monday)
CASE WHEN ISNULL(#startFromWeekend, 0) = 1
THEN CASE WHEN #delta > 0
THEN CASE #input_dw
WHEN 0 THEN -2
WHEN 6 THEN -1
END
ELSE CASE #input_dw
WHEN 0 THEN 1
WHEN 6 THEN 2
END
END
-- start calc from nearest weekday depending on delta direction
-- pos delta: next Monday from the weekend
-- neg delta: prev Friday from the weekend
ELSE CASE WHEN #delta > 0
THEN CASE #input_dw
WHEN 0 THEN 1
WHEN 6 THEN 2
END
ELSE CASE #input_dw
WHEN 0 THEN -2
WHEN 6 THEN -1
END
END
END
-- calculate: add weeks, add days, add initial correction offset
DECLARE #output DATE = DATEADD(DAY, #days + ISNULL(#offset, 0), DATEADD(WEEK, #weeks, #input))
-- finally, if output is weekend, add final correction offset depending on delta direction
SELECT
CASE WHEN (DATEPART(DW, #output) + ##DATEFIRST - 1) % 7 IN (0,6)
THEN CASE
WHEN #delta > 0 THEN DATEADD(DAY, 2, #output)
WHEN #delta < 0 THEN DATEADD(DAY, -2, #output)
END
ELSE #output
END
END
I could not find a satisfactory solution to this that I could understand, so I ended up mostly writing one myself. This started off structurally similar to Damien_The_Unbeliever's answer but diverged quite a bit as I couldn't get it to work.
My requirements
I'm using Redshift, so has to work there.
Negative number-of-days inputs must work (e.g. add -1 or -12 business days).
The output must be correct when input date is a weekday (e.g. Mon + 2 → Wed; Tue - 4 → previous Wed).
The solution must be documented.
Nice-to-haves
Sane output for weekend days. (I chose to roll weekend days to their following Mondays, so e.g. Sunday + 1 == Monday + 1 == Tuesday.)
Solution
Note: My company uses Periscope Data for BI which has a C-macro-like syntax sugar to define inline text replacements it calls Snippets (see docs). Should be easily translatable to pure SQL though -- feel free to suggest an edit to my answer if you've done that translation.
Snippet: add_business_days(date,num_days)
(dateadd(
day
, (
7 * (([num_days]) / 5) -- add whole weeks
+ (([num_days]) % 5) -- add remaining days after taking out whole weeks
+ case when ( -- if (
extract(dow from [roll_forward_to_weekday("[date]")]) -- day of week of "rolled forward" date (i.e. weekends → Monday)
+ (([num_days]) % 5) -- + remaining days after taking out whole weeks
not between 1 and 5 -- is NOT a weekday of the same week
) -- )
then sign([num_days])::int * 2 -- then increase magnitude of num_days by 2 to jump over the weekend
else 0
end
) -- start from the "rolled forward" date because adding business days to ..
, [roll_forward_to_weekday("[date]")] -- Saturday or Sunday is equivalent to adding them to the following Monday.
-- (note: due to ^, add_business_days(Saturday or Sunday,0) == Monday)
))
Snippet: roll_forward_to_weekday(date)
(dateadd(
day
, case extract(dayofweek from([date]))
when 6 /* Saturday */ then 2
when 0 /* Sunday */ then 1
else 0
end
, ([date])
))
Very late to the party, but I stumbled upon the very same question. And though there are a myriad of answers here, I just wanted to add my solution, b/c the solutions here are:
Either not working with negative offsets
Or do not work with different ##DATEFIRST settings
Or are using loops for something which could be solved solely with modulus arithmetic.
or are overly complicated in their branching logic
Thus, here's my solution, which I validated using Excel's WORKDAY function for positive and negative offsets:
CREATE OR ALTER FUNCTION dbo.AddBusinessDays(#startdate AS DATETIME, #n AS INT)
RETURNS DATETIME
AS
BEGIN
DECLARE #result DATETIME;
DECLARE #nrweeks INT,
#nrdays INT;
DECLARE #wd TINYINT;
DECLARE #residdays SMALLINT;
SET #wd = ((DATEPART(DW, #startdate) - 1) + ##DATEFIRST) % 7;
--- 6 working days correspond to 1 full week and 1 extra day
SET #nrweeks = #n / 5;
SET #residdays = #n % 5;
/*
(1) transform working weeks into calendar weeks
(2) if residual days + starting day touches a saturday add 2 days for the weekend
(3) unless if we started on a saturday we should not count it, e.g. SAT + 1 WD would result in 1 + 2 => TUE, but it should be MON so 1 + 2 - 1
(4) if we have a full working week w/o residual days and started on the weekend remove touching condition altogether, e.g. SAT + 5 WD: 7 + 2 - 1 => SUN, but it should be FRI, so 7 + 2 - 1 - 2
(1a) - (4a) likewise but for negative logic, i.e. all logic regarding SAT should be logic regarding SUN and signs have to be switched
*/
IF #n = 0
SET #nrdays = 0;
ELSE IF #n > 0
SET #nrdays = #residdays + 7 * #nrweeks + --- (1)
IIF(#wd + #residdays >= 6, 2, 0) + --- (2)
IIF(#wd = 6, -1, 0) + --- (3)
IIF(#residdays = 0 AND #wd % 6 = 0, -2, 0); --- (4)
ELSE
SET #nrdays = #residdays + 7 * #nrweeks + --- (1a)
IIF(#wd + #residdays <= 0, -2, 0) + --- (2a)
IIF(#wd = 0, 1, 0) + --- (3a)
IIF(#residdays = 0 AND #wd % 6 = 0, 2, 0); --- (4a)
SET #result = DATEADD(DAY, #nrdays, #startdate);
RETURN #result;
END
N.B. This solution is obviously made for T-SQL.
I am using the query below to get the number of the week in a month:
datepart(day, datediff(day, 0,TABLE.DATE), 102))/7 * 7)/7 + 1
Now I need to change the script that if a week ends in the next month, it should show 1 instead of 5.
Does anybody can help me?
Using Modulo by 4, you can get the month number 1 instead of 5.
For an example I tested with the 5th week and it result as 1:
DECLARE #TestDate AS DATETIME = '2016-07-29 10:00:00';
SELECT CASE ((DATEPART(DAY, DATEDIFF(DAY, 0, #TestDate)) /7 * 7) /7 + 1) % 4
WHEN 0 THEN 4
ELSE ((DATEPART(DAY, DATEDIFF(DAY, 0, #TestDate)) /7 * 7) /7 + 1) % 4 END
In your query, you wrongly used DATEPART. Actually it requires 2 parameters only.
I have a Execute SQL task in SSIS, which updates date in Database to today's date+3. But if suppose today is Thursday say(18/6/2015) and jobs executes then according to update query date in Database will be update to (21/6/2015) out of which 20th and 21st are Sat and Sunday. Instead i would want the date to be updated to 23/6/2015 i.e Tuesday( excluding Sat and Sunday). Please help!
I've made the following SELECT statement which may help you.
Using the DATEPART function you can discover which day of the week a sum of days will be.
DATEPART returns a number representing the day of the week of the date passed as parameter to the function, considering 1 is Sunday and 7 is Saturday.
select CASE
WHEN DATEPART(DW, GETDATE() + 4) = 7 THEN (SELECT GETDATE() + 6)
WHEN DATEPART(DW, GETDATE() + 5) = 1 THEN (SELECT GETDATE() + 5)
END As date
Using this example in an update statement:
UPDATE <your table>
SET dateofanything = (CASE
WHEN DATEPART(DW, GETDATE() + 3) = 7 THEN (SELECT GETDATE() + 5)
WHEN DATEPART(DW, GETDATE() + 3) = 1 THEN (SELECT GETDATE() + 4)
END As date)
I'm looking for a SQL Server UDF that will be equivalent to DATEPART(WEEK, #date), but will allow the caller to specify the first day of the week. Somewhat similar to MySql's WEEK function. E.g.:
CREATE FUNCTION Week (#date date, #firstdayofweek int)
RETURNS int
BEGIN
-- return result would be the same as:
-- SET DATEFIRST #firstdayofweek
-- DATEPART(WEEK, #date)
END
My application does not have the opportunity to call SET DATEFIRST.
Examples:
SELECT Week('2013-08-28', 2) -- returns 35
SELECT Week('2013-08-28', 3) -- returns 36
The above results would always be the same, regardless of SQL Server's value for ##DATEFIRST.
You could use something like this:
DATEPART(WEEK, DATEADD(DAY, 8 - #firstdayofweek, #date))
Instead of moving the first day of the week you are moving the actual date. Using this formula the first day of the week would be set using the same number values for days that MS SQL Server uses. (Sunday = 1, Saturday = 7)
I've found a couple of articles that helped me answer to derive an answer to this question:
Deterministic scalar function to get week of year for a date
http://sqlmag.com/t-sql/datetime-calculations-part-3
It may be possible to simplify this UDF, but it gives me exactly what I was looking for:
CREATE FUNCTION Week (#date DATETIME, #dateFirst INT)
RETURNS INT
BEGIN
DECLARE #normalizedWeekOfYear INT = DATEDIFF(WEEK, DATEADD(YEAR, DATEDIFF(YEAR, 0, #date), 0), #date) + 1
DECLARE #jan1DayOfWeek INT = DATEPART(WEEKDAY, DATEADD(YEAR, DATEDIFF(YEAR, 0, #date), 0) + ##DATEFIRST- 7) - 1
DECLARE #dateDayOfWeek INT = DATEPART(WEEKDAY, DATEADD(DAY, ##DATEFIRST- 7, #date)) - 1
RETURN #normalizedWeekOfYear +
CASE
WHEN #jan1DayOfWeek < #dateFirst AND #dateDayOfWeek >= #dateFirst THEN 1
WHEN #jan1DayOfWeek >= #dateFirst AND #dateDayOfWeek < #dateFirst THEN -1
ELSE 0
END
END
GO
Then, executing the following statements would return 35 and 36 respectively:
SELECT dbo.Week('2013-08-28', 2)
SELECT dbo.Week('2013-08-28', 3)
/*
No matter how ##DATEFIRST is
return result as
weekdayName,weekdayNumber
Mo 1
Tu 2
Wn 3
Th 4
Fr 5
Sa 6
Su 7
*/
CREATE FUNCTION dbo.fnFixWeekday
(
#currentDate date
)
RETURNS INT
AS
BEGIN
-- get DATEFIRST setting
DECLARE #ds int = ##DATEFIRST
-- get week day number under current DATEFIRST setting
DECLARE #dow int = DATEPART(dw,#currentDate)
RETURN 1+(((#dow+#ds) % 7)+5) % 7
END
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 return the date of the following Monday. I'm not bothered about any holidays, only weekends are excluded.
The problem is that this is currently done using a while loop, and it appears to be massively slowing down the stored procedure that uses it while generating a table. Does anyone know if there is any way to perform this calculation without while loops or cursors?
Just for information, this is the current function:
ALTER FUNCTION [dbo].[AddWorkDaysToDate]
(
#fromDate datetime,
#daysToAdd int
)
RETURNS datetime
AS
BEGIN
DECLARE #toDate datetime
DECLARE #daysAdded integer
-- add the days, ignoring weekends (i.e. add working days)
set #daysAdded = 1
set #toDate = #fromDate
while #daysAdded <= #daysToAdd
begin
-- add a day to the to date
set #toDate = DateAdd(day, 1, #toDate)
-- only move on a day if we've hit a week day
if (DatePart(dw, #toDate) != 1) and (DatePart(dw, #toDate) != 7)
begin
set #daysAdded = #daysAdded + 1
end
end
RETURN #toDate
END
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
This answer has been significantly altered since it was accepted, since the original was wrong. I'm more confident in the new query though, and it doesn't depend on DATEFIRST
I think this should cover it:
declare #fromDate datetime
declare #daysToAdd int
select #fromDate = '20130123',#DaysToAdd = 4
declare #Saturday int
select #Saturday = DATEPART(weekday,'20130126')
;with Numbers as (
select 0 as n union all select 1 union all select 2 union all select 3 union all select 4
), Split as (
select #DaysToAdd%5 as PartialDays,#DaysToAdd/5 as WeeksToAdd
), WeekendCheck as (
select WeeksToAdd,PartialDays,MAX(CASE WHEN DATEPART(weekday,DATEADD(day,n.n,#fromDate))=#Saturday THEN 1 ELSE 0 END) as HitWeekend
from
Split t
left join
Numbers n
on
t.PartialDays >= n.n
group by WeeksToAdd,PartialDays
)
select DATEADD(day,WeeksToAdd*7+PartialDays+CASE WHEN HitWeekend=1 THEN 2 ELSE 0 END,#fromDate)
from WeekendCheck
We split the time to be added into a number of weeks and a number of days within a week. We then use a small numbers table to work out if adding those few days will result in us hitting a Saturday. If it does, then we need to add 2 more days onto the total.
This answers is based on #ElmerMiller's answer.
It fixes the negative value on Sunday comment from #FistOfFury
Negative values don't work if the date passed in is Sunday
And the DATEFIRST setting comment from #Damien_The_Unbeliever
But this one does assume a particular DATEFIRST setting (7), which some of the others don't need.
Now the corrected function
CREATE FUNCTION[dbo].[AddBusinessDays](#Date DATE,#n INT)
RETURNS DATE AS
BEGIN
DECLARE #d INT,#f INT,#DW INT;
SET #f=CAST(abs(1^SIGN(DATEPART(DW, #Date)-(7-##DATEFIRST))) AS BIT)
SET #DW=DATEPART(DW,#Date)-(7-##DATEFIRST)*(#f^1)+##DATEFIRST*(#f&1)
SET #d=4-SIGN(#n)*(4-#DW);
RETURN DATEADD(D,#n+((ABS(#n)+(#d%(8+SIGN(#n)))-2)/5)*2*SIGN(#n)-#d/7,#Date);
END
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
Have you thought about pre-populating a look-up table that contains all of the working days (using your function) , for example WorkingDays(int DaySequenceId, Date WorkingDate), you can then use this table by selecting the DaySequenceId of the #fromDate and add #daysToAdd to get the new working date. Obviously this method also has the additional overhead of administering the WorkingDays table, but you could pre-populate it with the range of dates you expect. The other downside is the working dates that can be calculated will only be those contained within the WorkingDays table.
To expand on Amine's comment and Nate cook's answer above, the one-liner solution to this is:
declare #DaysToAdd int , #FromDate datetime
set #DaysToAdd=-5 --5 days prior is 3/28/14
set #FromDate='4/4/14'
select
DATEADD(day, (#DaysToAdd % 5)
+ CASE
WHEN ((##DATEFIRST + DATEPART(weekday, #FromDate)) % 7 + (#DaysToAdd % 5)) > 6 THEN 2
ELSE 0
END
, DATEADD(week, (#DaysToAdd / 5), #FromDate))
Note you can add or subtract days to go forwards and backwards in time, respectively.
*I know this is an old thread but found something extremely useful a while ago, modified it and got this.
select ((DATEADD(d,DATEDIFF(d,0,(DATEADD (d,2,#fromDate))),#numbOfDays)))*
Update: I am sorry in a haste to find a piece of code (in a single statement) and to avoid using a function, I posted incorrect code here.
Bit mentioned above can be used if the number of days you are adding is 7 or less.
I have changed the code with required parameters for better understanding.
Anyway, I ended up using what 'Nate Cook' has mentioned above. And used it as a single line of code. (Because I am restraining from using functions)
Nate's code
select(
DATEADD(day, (#days % 5) +
CASE ((##DATEFIRST + DATEPART(weekday, GETDATE()) + (#days % 5)) % 7)
WHEN 0 THEN 2
WHEN 1 THEN 1
ELSE 0 END, DATEADD(week, (#days / 5), GETDATE()))
)
I have tested all of the solutions proposed here and none of them work.
Here are some test scenarios that broke a lot of the above solutions.
(assuming Saturday and Sunday are the days you are excluding):
-Add 0 days to a Saturday - Expected result = Saturday
-Add 0 days to a Sunday - Expected result = Sunday
-Add 1 day to Friday - Expected result = the following Monday
-Add 1 day to Saturday - Expected result = the following Monday
-Add 1 day to Sunday - Expected result = the following Monday
-Add 3 days to Friday - Expected result = the following Wednesday
-Add 5 days to Saturday - Expected result = the following Friday
-Add 5 days to Friday - Expected result = the following Friday
-Subtract 1 day from Monday - Expected result = the previous Friday
-Subtract 1 day from Sunday - Expected result = the previous Friday
-Subtract 1 day from Saturday - Expected result = the previous Friday
-Subtract 3 days from Monday - Expected result = the previous Wednesday
-Subtract 5 days from Saturday - Expected result = the previous Monday
-Subtract 5 days from Monday - Expected result = the previous Monday
Here is what I wrote after reading this entire thread and picking the good pieces of logic:
CREATE FUNCTION [dbo].[BusinessDateAdd]
(
#FromDate DATE
,#DaysToAdd INT
)
RETURNS DATE
AS
BEGIN
--If there are no days to add or subtract, return the day that was passed in
IF #DaysToAdd = 0 RETURN #FromDate
DECLARE #Weeks INT
DECLARE #DMod INT
DECLARE #FromDateIndex INT
--number of weeks
SET #Weeks = #DaysToAdd/5
--remainder of days
SET #dmod = #DaysToAdd%5
--Get the FromDate day of the week, this logic standardizes the ##DateFirst to Sunday = 1
SET #FromDateIndex = (DATEPART(weekday, #FromDate) + ##DATEFIRST - 1) % 7 + 1
/*Splitting the addition vs subtraction logic for readability*/
--Adding business days
IF #DaysToAdd > 0
BEGIN
--If the FromDate is on a weekend, move it to the previous Friday
IF #FromDateIndex IN(1,7)
BEGIN
SET #FromDate = DATEADD(dd,CASE #FromDateIndex WHEN 1 THEN -2 WHEN 7 THEN -1 END,#FromDate)
SET #FromDateIndex = 6
END
SET #FromDate = DATEADD(dd,
CASE
--If the mod goes through the weekend, add 2 days to account for it
WHEN
((#FromDateIndex = 3 --Tuesday
AND #dmod > 3) --Days until Friday
OR
(#FromDateIndex = 4 --Wednesday
AND #dmod > 2)--Days until Friday
OR
(#FromDateIndex = 5 --Thursday
AND #dmod > 1)--Days until Friday
OR
(#FromDateIndex = 6 --Friday
AND #dmod > 0))--Days until Friday
THEN
#DMod+2
--Otherwise just add the mod
ELSE
#DMod
END, #FromDate)
END
--Subtracting business days
IF #DaysToAdd < 0
BEGIN
--If the FromDate is on a weekend, move it to the next Monday
IF #FromDateIndex IN(1,7)
BEGIN
SET #FromDate = DATEADD(dd,CASE #FromDateIndex WHEN 1 THEN 1 WHEN 7 THEN 2 END,#FromDate)
SET #FromDateIndex = 2
END
SET #FromDate = DATEADD(dd,
CASE
--If the mod goes through the weekend, subtract 2 days to account for it
WHEN
((#FromDateIndex = 5 --Thursday
AND #dmod < -3) --Days until Monday
OR
(#FromDateIndex = 4 --Wednesday
AND #dmod < -2)--Days until Monday
OR
(#FromDateIndex = 3 --Tuesday
AND #dmod < -1)--Days until Monday
OR
(#FromDateIndex = 2 --Monday
AND #dmod < 0))--Days until Monday
THEN
#DMod-2
--Otherwise just subtract the mod
ELSE
#DMod
END, #FromDate)
END
--Shift the date by the number of weeks
SET #FromDate = DATEADD(ww,#Weeks,#FromDate)
RETURN #FromDate
END
CREATE FUNCTION DateAddBusinessDays
(
#Days int,
#Date datetime
)
RETURNS datetime
AS
BEGIN
DECLARE #DayOfWeek int;
SET #DayOfWeek = CASE
WHEN #Days < 0 THEN (##DateFirst + DATEPART(weekday, #Date) - 20) % 7
ELSE (##DateFirst + DATEPART(weekday, #Date) - 2) % 7
END;
IF #DayOfWeek = 6 SET #Days = #Days - 1
ELSE IF #DayOfWeek = -6 SET #Days = #Days + 1;
RETURN #Date + #Days + (#Days + #DayOfWeek) / 5 * 2;
END;
This function can add and subtract business days regardless of the value of ##DATEFIRST. To subtract business days use a negative number of days.
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)
I don't have Sql Server at the moment to test but this is the idea:
ALTER FUNCTION [dbo].[AddWorkDaysToDate]
(
#fromDate datetime,
#daysToAdd int
)
RETURNS datetime
AS
BEGIN
DECLARE #dw integer
DECLARE #toDate datetime
set datefirst 1
set #toDate = dateadd(day, #daysToAdd, #fromDate)
set #dw = datepart(dw, #toDate)
if #dw > 5 set #toDate = dateadd(day, 8 - #dw, #toDate)
RETURN #toDate
END
Thanks Damien for the code. There was a slight error in the calcs in that it added only 1 day for the sunday, and that when the number of business days crossed a weekend (but did not land in the weekend) the extra 2 days was not taken into account. Here is a modified version of Damiens code that works with the default datefirst at 7. Hope this helps.
CREATE FUNCTION [dbo].[fn_AddBusinessDays]
(
#StartDate datetime,
#BusinessDays int
)
RETURNS datetime
AS
BEGIN
DECLARE #EndDate datetime
SET #EndDate = DATEADD(day, #BusinessDays%5 +
CASE
WHEN DATEPART(weekday,#StartDate) + #BusinessDays%5 > 6 THEN 2
ELSE 0
END,
DATEADD(week,#BusinessDays/5,#StartDate))
RETURN #EndDate
END
GO
The question's accepted answer produces incorrect results. E.g. select #fromDate = '03-11-1983', #DaysToAdd = 3 results in 03-14-1983 while 03-16-1983 is expected.
I posted a working solution here, but for completeness sake I will also add it here. If you are interested in the details of the two methods go visit my original answer. If not, simply copy/pasta this into your SQL project and use UTL_DateAddWorkingDays
Note that my solution only works if DATEFIRST is set to the default value of 7.
Test Script used to test various methods
CREATE FUNCTION [dbo].[UTL_DateAddWorkingDays]
(
#date datetime,
#days int
)
RETURNS TABLE AS RETURN
(
SELECT
CASE
WHEN #days = 0 THEN #date
WHEN DATEPART(dw, #date) = 1 THEN (SELECT Date FROM [dbo].[UTL_DateAddWorkingDays_Inner](DATEADD(d, 1, #date), #days - 1))
WHEN DATEPART(dw, #date) = 7 THEN (SELECT Date FROM [dbo].[UTL_DateAddWorkingDays_Inner](DATEADD(d, 2, #date), #days - 1))
ELSE (SELECT Date FROM [dbo].[UTL_DateAddWorkingDays_Inner](#date, #days))
END AS Date
)
CREATE FUNCTION [dbo].[UTL_DateAddWorkingDays_Inner]
(
#date datetime,
#days int
)
RETURNS TABLE AS RETURN
(
SELECT
DATEADD(d
, (#days / 5) * 7
+ (#days % 5)
+ (CASE WHEN ((#days%5) + DATEPART(dw, #date)) IN (1,7,8,9,10) THEN 2 ELSE 0 END)
, #date) AS Date
)
This is what I use:
SET DATEFIRST 1;
SELECT DATEADD(dw, (**NumberToAdd**/5)*7+(**NumberToAdd** % 5) +
(CASE WHEN DATEPART(dw,**YourDate**) + (**NumberToAdd** % 5) > 5
THEN 2 ELSE 0 END), **YourDate**) AS IncrementedDate
FROM YourTable t
The "SET DATEFIRST 1;" part is necessary to set Monday as the first day of the week.
WITH get_dates
AS
(
SELECT getdate() AS date, 0 as DayNo
UNION ALL
SELECT date + 1 AS date, case when DATEPART(DW, date + 1) IN (1,7) then DayNo else DayNo + 1 end
FROM get_dates
WHERE DayNo < 4
)
SELECT max(date) FROM get_dates
OPTION (MAXRECURSION 0)
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')
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.
This SQL function works similar to Excel WORKDAY function.
Hope it can help you.
CREATE FUNCTION [dbo].[BusDaysDateAdd]
(
#FromDate date,
#DaysToAdd int
)
RETURNS date
AS
BEGIN
DECLARE #Result date
DECLARE #TempDate date
DECLARE #Remainder int
DECLARE #datePartValue int
SET #TempDate = (DATEADD(week, (#DaysToAdd / 5), #FromDate))
SET #Remainder = (#DaysToAdd % 5)
SET #datePartValue = DATEPART(weekday, #TempDate)
SET #Result = DATEADD(day,#Remainder + CASE WHEN #Remainder > 0 AND #datePartValue = 7 THEN 1
WHEN #Remainder >= 1 AND #datePartValue = 6 THEN 2
WHEN #Remainder >= 2 AND #datePartValue = 5 THEN 2
WHEN #Remainder >= 3 AND #datePartValue = 4 THEN 2
WHEN #Remainder >= 4 AND #datePartValue = 3 THEN 2
WHEN #Remainder >= 5 AND #datePartValue = 2 THEN 2
ELSE 0 END, #TempDate)
RETURN #Result
END
GO
Reference
I'm a little late to this party but I wound up writing my own version of this, because of drawbacks in the other solutions. Specifically this version addresses counting backwards, and starting on weekends.
There's an ambiguous situation that could arise, if you add zero business days to a weekend date. I've kept the date the same, but you can leave out this check if you always want to force a weekday to be returned.
CREATE FUNCTION [dbo].[fn_AddBusinessDays]
(
#date datetime,
#businessDays int
)
RETURNS datetime
AS
BEGIN
--adjust for weeks first
declare #weeksToAdd int = #businessDays / 7
declare #daysToAdd int = #businessDays % 7
--if subtracting days, subtract a week then offset
if #businessDays < 0 begin
set #daysToAdd = #businessDays + 5
set #weeksToAdd = #weeksToAdd - 1
end
--saturday becomes zero using the modulo operator
declare #originalDayOfWeek int = datepart(dw, #date) % 7
declare #newDayOfWeek int = datepart(dw, dateadd(d, #daysToAdd, #date)) % 7
--special case for when beginning date is weekend
--adding zero on a weekend keeps the same date. you can remove the <> 0 check if you want Sunday + 0 => Monday
declare #dateOffset int = case
when #businessDays <> 0 and #originalDayOfWeek = 0 then 2
when #businessDays <> 0 and #originalDayOfWeek = 1 then 1
when #businessDays <> 0 and #newDayOfWeek < #originalDayOfWeek then 2
else 0
end
-- Return the result of the function
return dateadd(d, #daysToAdd + #dateOffset, dateadd(ww, #weeksToAdd, #date))
END
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
I just tested the accepted answer and found that it does not work when Sunday is the start day.
You need to add the following under the Select #Saturday line item:
SELECT #fromDate = CASE WHEN DATEPART(weekday,#fromDate) = 1 THEN DATEADD(day,1,#fromDate) ELSE #fromDate END
Sigh. I can't believe after all these decades there's still no : a) standard "DateAddWorkDays" in Microsoft SQL Server (even though Microsoft has had a WorkDay Function in Excel forever) and b) clear solution in here or anywhere else I can find that handles all issues people have raised.
Here's a solution I developed that addresses the following issues that seemingly all the above answers here and elsewhere I've been able to find has one or more of. This handles:
Mnemonic identifier names.
Comments explaining code that's not clear.
Not checking every single work day needing to be incremented (i.e.
much less than O(n) complexity).
Negative work day increments.
Allowing non-12 am time portion to be passed in (so you won't have to strip it first).
Retaining the passed-in time portion, if any, in the result (in case you need the exact time x-business days ahead/ago).
Weekend day names in languages other than English.
##DateFirst values other than the default (7 aka U.S.).
Specifying a custom list of non-weekend non-working days.
Allowing list of non-weekend non-working days to work if passed-in date has a non-12 am time.
Returning starting date-time if # work days increment is 0 even if starting date-time is on a non-working day.
Moving to the next / previous working day first before starting to increment / decrement working days, respectively. NOTE: This differs from Excel's WorkDay Function, but I believe this is more useful and intuitive. Ex. If you get an inquiry / order on a weekend day, and you have an SLA (i.e. response time, delivery date) of 1 business day, you shouldn't have to respond / deliver until 1 full working day has passed (regardless of how many adjacent non-working days preceeded it).
Skipping any additional weekends and/or non-working weekdays that may have been spanned after adding any non-working weekdays back in that may have been spanned when adding initial weekends spanned when adding # of working days alone - and repeating until no longer necessary.
SUGGESTIONS: Of course, as with any recursive algorithm, this one can be converted to an iterative one (by implementing your own stack, i.e. with a Temp Table), but I think the 32 nesting levels is way more than enough for the vast majority of real-world use cases. Also, of course, you can make it more generic / portable by passing in the non-working weekday dates as a Table-Valued Parameter vs. a hard-coded Table reference.
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- ===================================================================================================================================
-- Author: Tom
-- Create date: 03/13/2017
-- Description: Add specified # of working days (+/-) to a specified date-time assuming existence of a list of non-work weekday
-- dates (incl. holidays, weather days, utility outage days, fire days, etc.) in the 'NonWorkDayDate' Column of a 'NonWorkWeekday'
-- Table. If specified # working days is 0, the specified date-time is returned. Working days are not added until the specified
-- date-time has first been incremented (+/-) to the next working day in the direction of the working days increment.
-- NOTE: Uses a forumla (vs. O(n) loop) that uses recusion whenever days incremented (incl. weekends) spans non-work weekdays.
-- !!!WARNING!!!: Will exceed SQL Server nesting level (32) if abs (# of working days) < ~1 / 32 adjacent non-working days.
-- Parameters:
-- #RefDateTime DateTime: Reference date-time to which to add '#WorkDaysIncrement'.
-- #WorkDaysIncrement Int: # of working days (+/-) to add # to the '#RefDateTime'.
-- Returns:
-- 1. Result of #RefDateTime + #WorkDaysIncrement (skipping weekend and holiday dates and retaining the #RefDateTime's time).
-- ===================================================================================================================================
CREATE FUNCTION [dbo].[AddWorkDays_Recursive]
(
-- Add the parameters for the function here
#RefDateTime datetime,
#WorkDaysIncrement int
)
RETURNS DateTime
AS
BEGIN
-- If no days to increment, return passed in date-time (even if weekend day).
if (#WorkDaysIncrement = 0) return #RefDateTime
-- Set the one-day increment used to add or subtract one calendar/work day.
declare #OneDayIncrement int = sign(#WorkDaysIncrement)
-- Initialize # of calendar days added to 0.
declare #DaysAdded int = 0
-- Set reference date to date (i.e. excl. time) of reference date-time.
declare #RefDate datetime = convert
(
date,
convert
(
varchar(10),
#RefDateTime,
101
)
)
--end declare #RefDate
-- Initialize result date to reference date
declare #ResultDate datetime = #RefDate
-- Set U.S. Weekday # to the 1-based U.S. weekday # result date.
declare #USWeekdayNumber tinyint = ((datepart(weekday, #ResultDate) + ##datefirst - 1) % 7) + 1 -- Sun to Sat = 1 to 7
-- If result date is now on a weekend day, set # of weekend days increment so that we can move it +/- 1 to 2 days to next weekday.
declare #WeekendDaysInc smallint =
(
case (#USWeekdayNumber)
when 1 then --Sunday
case
when (#OneDayIncrement > 0) then 1
else -2
end
--end when 1 --Sunday
when 7 then --Saturday
case
when (#OneDayIncrement > 0) then 2
else -1
end
--end when 7 then --Saturday
else 0 -- Not Weekend Day #
end -- case (#USWeekdayNumber)
) -- end declare #WeekendDaysInc smallint =
-- Increment # of calendar days added by # of weekend days increment
set #DaysAdded += #WeekendDaysInc
-- Increment result date by # of weekend days increment
set #ResultDate += #WeekendDaysInc
-- Set # of work weeks increment to # of full 5-day increments in the # (+/-) of work days to increment.
declare #WorkWeeksIncrement int = #WorkDaysIncrement / 5
-- Increment # of calendar days added by 7 times # of work weeks increment, i.e. to add weekday + weekend days for full weeks.
set #DaysAdded += #WorkWeeksIncrement * 7
-- Set result date after full weeks added to reference date + # of calendar days
declare #AfterFullWeeksResultDate datetime = #ResultDate + #DaysAdded
-- Set # partial-work week days to # (+/-) of work days to increment left after adding full weeks.
declare #PartialWorkWeekDays int = #WorkDaysIncrement % 5
-- Increment # of calendar days added by # partial-work week days
set #DaysAdded += #PartialWorkWeekDays
-- Set result date after partial week added to result date after full weeks added + # partial work week days
declare #AfterPartialWeekResultDate datetime = #AfterFullWeeksResultDate + #PartialWorkWeekDays
--Set result date to result date after partial week.
set #ResultDate = #AfterPartialWeekResultDate
-- Set After Full Weeks U.S. Weekday # to the 1-based U.S. weekday # result date.
declare #AfterFullWeeksUSWeekdayNumber tinyint =
(
((datepart(weekday, #AfterFullWeeksResultDate) + ##datefirst - 1) % 7) + 1 -- Sun to Sat = 1 to 7
)
-- Set After Partial Week U.S. Weekday # to the 1-based U.S. weekday # result date.
declare #AfterPartialWeekUSWeekdayNumber tinyint =
(
((datepart(weekday, #AfterPartialWeekResultDate) + ##datefirst - 1) % 7) + 1 -- Sun to Sat = 1 to 7
)
--If (incrementing and After Full Weeks U.S. Weekday # > #AfterPartialWeekUSWeekdayNumber)
-- or (decrementing and After Full Weeks U.S. Weekday # < #AfterPartialWeekUSWeekdayNumber), increment by (+/-) 2 to account for
-- the weekend that was spanned when partial-work week days were added.
if
(
(
(#OneDayIncrement > 0)
and (#AfterFullWeeksUSWeekdayNumber > #AfterPartialWeekUSWeekdayNumber)
)
or (
(#OneDayIncrement < 0)
and (#AfterFullWeeksUSWeekdayNumber < #AfterPartialWeekUSWeekdayNumber)
)
)
begin
set #WeekendDaysInc = 2 * #OneDayIncrement
set #DaysAdded += #WeekendDaysInc
set #ResultDate += #WeekendDaysInc
end -- if need to increment to account for weekend spanned by partial-work week days,
-- Set U.S. Weekday # to the 1-based U.S. weekday # result date.
set #USWeekdayNumber = ((datepart(weekday, #ResultDate) + ##datefirst - 1) % 7) + 1 -- Sun to Sat = 1 to 7
-- If result date is now on a weekend day, set # of weekend days increment so that we can move it +/- 1 to 2 days to next weekday.
set #WeekendDaysInc =
(
case (#USWeekdayNumber)
when 1 then --Sunday
case
when (#OneDayIncrement > 0) then 1
else -2
end
--end when 1 --Sunday
when 7 then --Saturday
case
when (#OneDayIncrement > 0) then 2
else -1
end
--end when 7 then --Saturday
else 0 -- Not Weekend Day #
end -- case (#USWeekdayNumber)
) -- end declare #WeekendDaysInc smallint =
-- Increment # of calendar days added by # of weekend days increment
set #DaysAdded += #WeekendDaysInc
-- Increment result date by # of weekend days increment
set #ResultDate += #WeekendDaysInc
-- Set non-work weedays count to # Rows where NonWorkDayDate between RefDate and ResultDate (if # of work days to increment > 0), else between
-- ResultDate and RefDate.
declare #NonWorkWeekdaysCount int =
(
select count(nw.NonWorkDayDate)
from NonWorkWeekday as nw
where
(
(#OneDayIncrement > 0)
and (nw.NonWorkDayDate between #RefDate and #ResultDate)
)
or (
(#OneDayIncrement < 0)
and (nw.NonWorkDayDate between #ResultDate and #RefDate)
)
--end select count(nw.NonWorkDayDate) from Holidate as nw
) -- end declare #HolidaysSpanned int =
-- Set result date-time to reference date-time + # of calendar days added
declare #ResultDateTime datetime = #RefDateTime + #DaysAdded
-- Set result date-time equal to result of adding (# of holidays x one-day increment).
set #ResultDateTime = dbo.AddWorkDays_Recursive
(
#ResultDateTime, -- #RefDateTime
#NonWorkWeekdaysCount * #OneDayIncrement -- #WorkDaysIncrement
)
--end set #ResultDateTime =
-- Return the result of the function
RETURN #ResultDateTime
END
GO
For Germany all of the answers don't work.
The only function I tested and works is a translation from an old Excel form here:
Set #EndDate=Dateadd(DAY,#DaysToAdd,#FromDate) +
Cast(((
CASE WHEN 5 <= DATEPART(weekday, #FromDate)%7
THEN 5
ELSE
DATEPART(weekday, #FromDate)%7
END)
-1 + #DaysToAdd )/5
as int)
* 2 -
(Case when DAtepart(weekday, #FromDate)=6 then 1 else 0 end)
--Refactoring my original answer... I've added the option to define the starting point of the calculation if the starting date happens to be a weekend day: start from that weekend day or shift to the nearest weekday depending on the direction of the delta.
DECLARE
#input DATE = '2019-06-15', -- if null, then returns null
#delta INT = 1, -- can be positive or negative; null => zero
#startFromWeekend BIT = 1 -- null => zero
-- input is null, delta is zero/null
IF #input IS NULL OR ISNULL(#delta, 0) = 0
SELECT #input
-- input is not null and has delta
ELSE
BEGIN
DECLARE
#input_dw INT = (DATEPART(DW, #input) + ##DATEFIRST - 1) % 7, -- input day of week
#weeks INT = #delta / 5, -- adjust by weeks
#days INT = #delta % 5 -- adjust by days
-- if input is a weekend day, offset it for proper calculation
-- !!important!!: depends on *your* definition of the starting date to perform calculation from
DECLARE #offset INT =
-- start calc from weekend day that is nearest to a weekday depending on delta direction
-- pos delta: effectively Sunday of the weekend (actual: prev Friday)
-- neg delta: effectively Saturday of the weekend (actual: next Monday)
CASE WHEN ISNULL(#startFromWeekend, 0) = 1
THEN CASE WHEN #delta > 0
THEN CASE #input_dw
WHEN 0 THEN -2
WHEN 6 THEN -1
END
ELSE CASE #input_dw
WHEN 0 THEN 1
WHEN 6 THEN 2
END
END
-- start calc from nearest weekday depending on delta direction
-- pos delta: next Monday from the weekend
-- neg delta: prev Friday from the weekend
ELSE CASE WHEN #delta > 0
THEN CASE #input_dw
WHEN 0 THEN 1
WHEN 6 THEN 2
END
ELSE CASE #input_dw
WHEN 0 THEN -2
WHEN 6 THEN -1
END
END
END
-- calculate: add weeks, add days, add initial correction offset
DECLARE #output DATE = DATEADD(DAY, #days + ISNULL(#offset, 0), DATEADD(WEEK, #weeks, #input))
-- finally, if output is weekend, add final correction offset depending on delta direction
SELECT
CASE WHEN (DATEPART(DW, #output) + ##DATEFIRST - 1) % 7 IN (0,6)
THEN CASE
WHEN #delta > 0 THEN DATEADD(DAY, 2, #output)
WHEN #delta < 0 THEN DATEADD(DAY, -2, #output)
END
ELSE #output
END
END
I could not find a satisfactory solution to this that I could understand, so I ended up mostly writing one myself. This started off structurally similar to Damien_The_Unbeliever's answer but diverged quite a bit as I couldn't get it to work.
My requirements
I'm using Redshift, so has to work there.
Negative number-of-days inputs must work (e.g. add -1 or -12 business days).
The output must be correct when input date is a weekday (e.g. Mon + 2 → Wed; Tue - 4 → previous Wed).
The solution must be documented.
Nice-to-haves
Sane output for weekend days. (I chose to roll weekend days to their following Mondays, so e.g. Sunday + 1 == Monday + 1 == Tuesday.)
Solution
Note: My company uses Periscope Data for BI which has a C-macro-like syntax sugar to define inline text replacements it calls Snippets (see docs). Should be easily translatable to pure SQL though -- feel free to suggest an edit to my answer if you've done that translation.
Snippet: add_business_days(date,num_days)
(dateadd(
day
, (
7 * (([num_days]) / 5) -- add whole weeks
+ (([num_days]) % 5) -- add remaining days after taking out whole weeks
+ case when ( -- if (
extract(dow from [roll_forward_to_weekday("[date]")]) -- day of week of "rolled forward" date (i.e. weekends → Monday)
+ (([num_days]) % 5) -- + remaining days after taking out whole weeks
not between 1 and 5 -- is NOT a weekday of the same week
) -- )
then sign([num_days])::int * 2 -- then increase magnitude of num_days by 2 to jump over the weekend
else 0
end
) -- start from the "rolled forward" date because adding business days to ..
, [roll_forward_to_weekday("[date]")] -- Saturday or Sunday is equivalent to adding them to the following Monday.
-- (note: due to ^, add_business_days(Saturday or Sunday,0) == Monday)
))
Snippet: roll_forward_to_weekday(date)
(dateadd(
day
, case extract(dayofweek from([date]))
when 6 /* Saturday */ then 2
when 0 /* Sunday */ then 1
else 0
end
, ([date])
))
Very late to the party, but I stumbled upon the very same question. And though there are a myriad of answers here, I just wanted to add my solution, b/c the solutions here are:
Either not working with negative offsets
Or do not work with different ##DATEFIRST settings
Or are using loops for something which could be solved solely with modulus arithmetic.
or are overly complicated in their branching logic
Thus, here's my solution, which I validated using Excel's WORKDAY function for positive and negative offsets:
CREATE OR ALTER FUNCTION dbo.AddBusinessDays(#startdate AS DATETIME, #n AS INT)
RETURNS DATETIME
AS
BEGIN
DECLARE #result DATETIME;
DECLARE #nrweeks INT,
#nrdays INT;
DECLARE #wd TINYINT;
DECLARE #residdays SMALLINT;
SET #wd = ((DATEPART(DW, #startdate) - 1) + ##DATEFIRST) % 7;
--- 6 working days correspond to 1 full week and 1 extra day
SET #nrweeks = #n / 5;
SET #residdays = #n % 5;
/*
(1) transform working weeks into calendar weeks
(2) if residual days + starting day touches a saturday add 2 days for the weekend
(3) unless if we started on a saturday we should not count it, e.g. SAT + 1 WD would result in 1 + 2 => TUE, but it should be MON so 1 + 2 - 1
(4) if we have a full working week w/o residual days and started on the weekend remove touching condition altogether, e.g. SAT + 5 WD: 7 + 2 - 1 => SUN, but it should be FRI, so 7 + 2 - 1 - 2
(1a) - (4a) likewise but for negative logic, i.e. all logic regarding SAT should be logic regarding SUN and signs have to be switched
*/
IF #n = 0
SET #nrdays = 0;
ELSE IF #n > 0
SET #nrdays = #residdays + 7 * #nrweeks + --- (1)
IIF(#wd + #residdays >= 6, 2, 0) + --- (2)
IIF(#wd = 6, -1, 0) + --- (3)
IIF(#residdays = 0 AND #wd % 6 = 0, -2, 0); --- (4)
ELSE
SET #nrdays = #residdays + 7 * #nrweeks + --- (1a)
IIF(#wd + #residdays <= 0, -2, 0) + --- (2a)
IIF(#wd = 0, 1, 0) + --- (3a)
IIF(#residdays = 0 AND #wd % 6 = 0, 2, 0); --- (4a)
SET #result = DATEADD(DAY, #nrdays, #startdate);
RETURN #result;
END
N.B. This solution is obviously made for T-SQL.