create function dbo.f_countweekdays
(
@DOW int,
@StartDate datetime,
@EndDate datetime
)
returns int
begin
return
( select datediff(wk, T2.St, T2.En) -
case when T1.SDOW > @DOW then 1 else 0 end -
case when T1.EDOW < @DOW then 1 else 0 end
from (select datepart(dw, @StartDate),
datepart(dw, @EndDate)) as T1(SDOW, EDOW)
cross apply (select dateadd(d, - T1.SDOW, @StartDate),
dateadd(d, 7 - T1.EDOW, @EndDate)) as T2(St, En))
end