CREATE FUNCTION fnc_NumberOfWeekEnds(@dFrom DATETIME, @dTo DATETIME)

RETURNS INT AS

BEGIN

Declare @weekends int

Set @weekends = 0

While @dFrom <= @dTo Begin

If ((datepart(dw, @dFrom) = 1) OR (datepart(dw, @dFrom) = 7))

Set @weekends = @weekends + 1

Set @dFrom = DateAdd(d, 1, @dFrom)

End

Return (@weekends)

END

GO

Execute the the function

SELECT fnc_NumberOfWeekEnds('2/27/2013','3/10/2013')

Reference with other date parts