month of week of first day and last date using sqlserver

declare @end_week datetime,@week_number int
declare @start_week datetime,@today datetime
set @today=GETDATE()
set @week_number=2
set @today = dateadd(wk, @week_number- datepart(wk,@today), @today)
set @start_week = dateadd(d, 1 - DATEPART(dw, @today), @today)
set @end_week = dateadd(d,6,@start_week )
select @start_week,@end_week

First and Last Date of Last,Current and Next month using sqlserver 2008

DECLARE @Date DATETIME
SELECT @Date = GETDATE()
SELECT CONVERT(VARCHAR(25),DATEADD(dd,-(DAY(@Date)),@Date),101) ,
'LastDayof PreviousMonth'
UNION
SELECT CONVERT(VARCHAR(25),DATEADD(dd,-(DAY(@Date)-1),@Date),101) AS Date_Value,
'FirstDayofCurrentMonth' AS Date_Type
UNION
SELECT CONVERT(VARCHAR(25),@Date,101) AS Date_Value,
'Today' AS Date_Type
UNION
SELECT CONVERT(VARCHAR(25),DATEADD(dd,-(DAY(DATEADD(mm,1,@Date))),DATEADD(mm,1,@Date)),101) ,
'LastDayofCurrentMonth'
UNION
SELECT CONVERT(VARCHAR(25),DATEADD(dd,-(DAY(DATEADD(mm,1,@Date))-1),DATEADD(mm,1,@Date)),101) ,
'FirstDayofNextMonth'
GO