Using Silverlight in Enterprise: RAD of User Friendly Database Access

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[f_Get_WeekDay]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_Get_WeekDay]
GO

/*
  Purpose: Get First or Last Week Day 
           where @ToDay is interested date
                 @MonthIncrement is increment (For example: -1 is previous week;
                                                             0 is current week; 
                                                             1 next week and so on
                 @FirstLast: 'F' is First; 
                             'L' is Last)
*/

CREATE FUNCTION dbo.f_Get_WeekDay( @ToDay          datetime ,
                                   @MonthIncrement int,
                                   @FirstLast      char(1))
  RETURNS datetime
AS
BEGIN
  set @ToDay = convert(datetime, convert( varchar(30), @ToDay, 103), 103)
     return case @FirstLast
              when 'F' then @ToDay 
                            - dbo.f_GetProperWeekDay(DATEPART ( dw , @ToDay )) + 1
                            + @MonthIncrement * 7
              when 'L' then @ToDay 
                            + 7 - dbo.f_GetProperWeekDay(DATEPART ( dw , @ToDay ))
                            + @MonthIncrement * 7
              else null
            end 
END

GO