Question

I have seen a number of postings regarding how to create an SQL Server function that will add a given number of working days to a date. But, none of them calculate exactly the way I need. We have a function that is currently done in code but that I want to move to a native SQL Server function (for use by stored procedures and in queries). We give our customers 5 working days to collect cargo before we start assessing storage charges. The 5 working days exclude weekends and holidays (we have a table with the holiday dates). The trick here is that I need to get the date immediately after the 5 working days regardless of whether it is a weekend or holiday. So I need the function to return the last working date, NOT the first working day after. So, for example:

Oct 20th (Sat) plus 5 working days = Oct 26th (Fri)
Oct 21st (Sun) plus 5 working days = Oct 26th (Fri)
Oct 22nd (Mon) plus 5 working days = Oct 29th (Mon)
May 19th (Sat) plus 5 working days with May 21st a holiday = May 28th

The 5 working days is the current allotment, but this may change in the future so the number of working days needs to be a parameter. Also, the function may be used over fairly large datasets so I would prefer doing this without loops. We are running SQL Server 2008.

Edit: This is not a duplicate of “Add business days to date in SQL without loops” as they want the ending date to be a working day. I want my ending date to be whatever date immediately follows the last grace day (ie: 5 working days Mon to Fri I want the Sat date returned, NOT the following Mon).

Answer 1

create table holidays (
  date date);
GO

create function dbo.findWorkDayAfter(@date datetime, @days int)
returns date as
begin
return (
  select thedate
  from (
  select thedate=dateadd(d,v.day,cast(@date as date)),
         rn=row_number() over (order by v.day)
  from (values(1),(2),(3),(4),(5),(6),(7),(8),(9),(10))v(day)
  left join holidays h on h.date = dateadd(d,v.day,cast(@date as date))
  where h.date is null and left(datename(dw,dateadd(d,v.day,cast(@date as date))),1) <> 'S'
  ) x
  where @days = rn
  )
end
GO

Unless you have long holidays, 10 days should be enough to find the 5th next working day. Increase it if you need to.

If you need a larger number of business days from a date, you can use this which will cater for a year or three.

alter function dbo.findWorkDayAfter(@date datetime, @days int)
returns date as
begin
return (
  select thedate
  from (
  select thedate=dateadd(d,v.number,cast(@date as date)),
         rn=row_number() over (order by v.number)
  from master..spt_values v
  left join holidays h on h.date = dateadd(d,v.number,cast(@date as date))
  where h.date is null and left(datename(dw,dateadd(d,v.number,cast(@date as date))),1) <> 'S'
    and v.number >= 1 and v.type='p'
  ) x
  where @days = rn
  )
end
GO