How do I add to some date excluding weekends using SQL Server? - sql

Question

For example:
#dtBegin = '2012-06-29'
#input = 20
I want the output to be '2012-07-27'.

Answer 1

I had to tackle the same problem in my project. Gordon Lionoff's solution got me on the right track but did not always produce the right result. I also have to take in account dates that start in a weekend. I.e. adding 1 business day to a saturday or sunday should result in a monday. This is the most common approach to handling business day calculation.
I've created my own solution based on Gordon Linoff's function and Patrick McDonald's excellent C# equivalent
NOTE: My solution only works if DATEFIRST is set to the default value of 7. If you use a different DATEFIRST value, you will have to change the 1, 7 and (1,7,8,9,10) bits.
My solution consists of two functions. An "outer" function that handles edge cases and an "inner" function that performs the actual calculation. Both functions are table-valued functions so they will actually be expanded into the implementing query and fed through the query optimizer.
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
)
As you can see, the "outer" function handles:
When adding no days, return the original date. This will keep saturday and sunday dates intact.
When adding days to a sunday, start counting from monday. This consumes 1 day.
When adding days to a saturday, start counting from monday. This consumes 1 day.
In all other cases, perform the usual calculation
_
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
)
The "inner" function is similar to Gordon Linoff's solution, except it accounts for dates crossing weekend boundaries but without crossing a full week boundary.
Finally, I created a test script to test my function. The expected values were generated using Patrick McDonald's excellent C# equivalent and I randomly cross-referenced this data with this popular calculator.

Answer 2

You can do this without resorting to a calendar table or user defined function:
dateadd(d,
(#input / 5) * 7 + -- get complete weeks out of the way
mod(#input, 5) + -- extra days
(case when ((#input%5) + datepart(dw, #dtbegin)%7) in (7, 1, 8) or
((#input%5) + datepart(dw, #dtbegin)%7) < (#input%5)
then 2
else 0
end),
#dtbegin
)
I'm not saying this is pretty. But sometimes arithmetic is preferable to a join or a loop.

Answer 3

This is what I've 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.

Answer 4

I realize I'm about 8 years late to this party... But I took Martin's answer and updated it to:
1. a single scalar function instead of 2 nested table-valued functions
I tested using his original test script and my function passes too. Also, it seems the rebuild to a scalar function has a slight positive impact on performance. Both versions seem to benefit equally from 'buffer caching', the scalar version performing up to 25% better non-cached and up to 40% better cached. Disclaimer: I just ran both versions a bunch of times and recorded the times, I did not do any decent performance testing.
2. include support for DATEFIRST is either Monday, Saturday or Sunday
I feel a UDF should be agnostic to the datefirst setting. I'm in Europe and Monday is the default here. The original function would not work without adaptation.
According to wikipedia Monday, Saturday and Sunday are the only real world first days of the week. Support for other could easily be added, but would make the code more bulky and I have a hard time envisioning a real world use case.
CREATE FUNCTION dbo.fn_addWorkDays
(
#date datetime,
#days int
)
RETURNS DATETIME
AS
BEGIN
IF NOT ##DATEFIRST IN (1,6,7) BEGIN --UNSUPPORTED DATE FIRST
RETURN NULL
/* MONDAY = FRIST DAY */
END ELSE IF #days = 0 BEGIN
RETURN #date
END ELSE IF ##DATEFIRST = 1 AND DATEPART(dw, #date) = 7 BEGIN --SUNDAY
SET #date = DATEADD(d, 1, #date)
SET #days = #days - 1
END ELSE IF ##DATEFIRST = 1 AND DATEPART(dw, #date) = 6 BEGIN --SATURDAY
SET #date = DATEADD(d, 2, #date)
SET #days = #days - 1
/* SATURDAY = FRIST DAY */
END ELSE IF ##DATEFIRST = 7 AND DATEPART(dw, #date) = 2 BEGIN --SUNDAY
SET #date = DATEADD(d, 1, #date)
SET #days = #days - 1
END ELSE IF ##DATEFIRST = 7 AND DATEPART(dw, #date) = 1 BEGIN --SATURDAY
SET #date = DATEADD(d, 2, #date)
SET #days = #days - 1
/* SUNDAY = FRIST DAY */
END ELSE IF ##DATEFIRST = 7 AND DATEPART(dw, #date) = 1 BEGIN --SUNDAY
SET #date = DATEADD(d, 1, #date)
SET #days = #days - 1
END ELSE IF ##DATEFIRST = 7 AND DATEPART(dw, #date) = 7 BEGIN --SATURDAY
SET #date = DATEADD(d, 2, #date)
SET #days = #days - 1
END
DECLARE #return AS dateTime
SELECT #return =
DATEADD(d
, (#days / 5) * 7
+ (#days % 5)
+ (CASE
/* MONDAY = FRIST DAY */
WHEN ##DATEFIRST = 1 AND ((#days%5) + DATEPART(dw, #date)) IN (6,7,8,9) THEN 2
/* SATURDAY = FRIST DAY */
WHEN ##DATEFIRST = 7 AND ((#days%5) + DATEPART(dw, #date)) IN (1,2,8,9,10) THEN 2
/* SUNDAY = FRIST DAY */
WHEN ##DATEFIRST = 7 AND ((#days%5) + DATEPART(dw, #date)) IN (1,7,8,9,10,11) THEN 2
ELSE 0
END)
, #date)
RETURN #return
END
I hope this might benefit someone!

Answer 5

you can use the below mentioned code for exclude weekends
go
if object_id('UTL_DateAddWorkingDays') is not null
drop function UTL_DateAddWorkingDays
go
create FUNCTION [dbo].[UTL_DateAddWorkingDays]
(
#date datetime,
#daysToAdd int
)
RETURNS date
as
begin
declare #daysToAddCnt int=0,
#Dt datetime
declare #OutTable table
(
id int identity(1,1),
WeekDate date,
DayId int
)
while #daysToAdd>0
begin
set #Dt=dateadd(day,#daysToAddCnt,#date)
--select #daysToAddCnt cnt,#Dt date,DATEPART(weekday,#Dt) dayId,#daysToAdd daystoAdd
if(DATEPART(weekday,#Dt) <>7 and DATEPART(weekday,#Dt)<>1)
begin
insert into #outTable (WeekDate,DayId)
select #Dt,DATEPART(weekday,DATEADD(day,#daysToAddCnt,#Dt))
set #daysToAdd=#daysToAdd-1
end
set #daysToAddCnt=#daysToAddCnt+1
end
select #Dt=max(WeekDate) from #outTable
return #Dt
end

Answer 6

what about this?
declare #d1 date='2012-06-29'
declare #days int=20
select dateadd(dd,#days,#d1)
select dateadd(dd,case DATEPART(dw,t1.d) when 6 then +2 when 7 then +1 else +0 end,t1.d)
from
(
select dateadd(dd,CEILING((convert(float,#days)/5)*2)+#days,#d1)d
)t1
i found how many we in the range by CEILING((convert(float,#days)/5)*2)
then i added them to date and at the end i check if is a saturday or sunday and i add 1 or 2 days.