Start dates and end dates in C#

DateTime baseDate = DateTime.Today;

        var today = baseDate;

        var yesterday = baseDate.AddDays(-1);

        var thisWeekStart = baseDate.AddDays(-(int)baseDate.DayOfWeek);

        var thisWeekEnd = thisWeekStart.AddDays(7).AddSeconds(-1);

        var lastWeekStart = thisWeekStart.AddDays(-7);

        var lastWeekEnd = thisWeekStart.AddSeconds(-1);

        var thisMonthStart = baseDate.AddDays(1 - baseDate.Day);

        var thisMonthEnd = thisMonthStart.AddMonths(1).AddSeconds(-1);

        var lastMonthStart = thisMonthStart.AddMonths(-1);

        var lastMonthEnd = thisMonthStart.AddSeconds(-1);

Get number of weekends between two dates using sql server

This function will return the total number of weekends in two dates

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