sqlserver：某年份某月份 是否在某时间段内的函数

如题：今日碰到这个问题，比较郁闷，干脆自己写了个函数

-- 
-- IF OBJECT_ID (N'f_dtbj') IS NOT NULL
-- DROP FUNCTION f_dtbj
-- GO

create function f_dtbj(@year int,@month int,@dt1 datetime,@dt2 datetime)
returns  int 
as 
begin

   declare @dt DateTime
   declare @dtDay int
   set @dt=convert(datetime,convert(varchar,@year)+'-'+convert(varchar,@month)+'-1')

   select @dtDay=day(dateadd(dd,-1,cast(convert(varchar(6),dateadd(mm,1,@dt),112)+'01' as datetime))) 
    

   declare @inx int
   declare @k int
   declare @x1 int
   declare @x2 int
   set @k=1

   while(@k<=@dtDay)
      begin
      set @dt=convert(datetime,convert(varchar,@year)+'-'+convert(varchar,@month)+'-'+convert(varchar,@k))
      select @x1=datediff(month,@dt1,@dt)
      select @x2=datediff(month,@dt,@dt2)
      if @x1>=0 and @x2>=0 --在时间段里
          begin
          set @k=@dtDay+1 --跳出
          set @inx= 1
          end
      else
          begin
          set @k=@k+1
          set @inx=0
          end
      end

   return @inx
end