sql 以工作日計算起始年假的計算時間範圍

--以工作日計算起始年假的計算時間範圍
 declare @settoday smalldatetime,@birthday smalldatetime,@year varchar(10),@month varchar(10),@day varchar(10),@enddate datetime,@stardate datetime,@AnnualNumber int,@AnnualTotal int,@Surplus int
  set @settoday='2013-05-04'--現在日期
 set @birthday='2004-04-26' ---進公司日期
 set @year=DateName(Year,@settoday)
 set @month=DateName(Month,@birthday)
 set @day=DateName(Day,@birthday)
 --
 set @enddate=cast(@year+'-'+@month+'-'+@day as datetime)
 select @month
 select @enddate
 if(@enddate>=@settoday)
 begin
     set @stardate=dateadd(year,-1,@enddate) --減一年
 end
 else
 begin
     set @enddate=dateadd(year,1,@enddate)
     set @stardate=cast(@year+'-'+@month+'-'+@day as datetime)
 end
 select @stardate AS '起始計算日期'
 select @enddate AS '結束計算日期'