sql server 取当天所在第几周

declare @datetime datetime;;
set @datetime=getdate();
select dateadd(day,1-(datepart(weekday,@datetime)),@datetime) as dStartDate, ----取本周开始日期   
dateadd(day,1-(datepart(weekday,@datetime))+6,@datetime) as dEndDate,----取本周截至日期   
datepart(year,dateadd(day,1-(datepart(weekday,@datetime)),@datetime)) as iYear,----取所在月份   
datepart(month,dateadd(day,1-(datepart(weekday,@datetime)),@datetime)) as iMonth,----取所在月份   
datepart(day,dateadd(day,1-(datepart(weekday,@datetime)),@datetime))/7 + 1 as iWeekNum ----所在