How To Calculate the Number of Week Days Between two Dates

How To Calculate the Number of Week Days Between two Dates
declare @StartDay datetime
declare @EndDay datetime
set @StartDay = getdate()-30
set @EndDay = getdate()
select DateDiff(dd, @StartDay, @EndDay) - DateDiff(ww, @StartDay, @EndDay)*2
If you have a table of holidays, then you can simply subtract them out as well:
declare @StartDay datetime
declare @EndDay datetime
set @StartDay = getdate()-30
set @EndDay = getdate()
select DateDiff(dd, @StartDay, @EndDay) -
DateDiff(ww, @StartDay, @EndDay)*2 -
(select count(*) from holidays where holiday_date between @StartDay and @EndDay)