关于replace替换的有关问题_Sql Server

关于replace替换的问题
程序一

declare @begin as nvarchar(1500),@end as nvarchar(1500),@a as nvarchar(150) ,@b as nvarchar(150)
declare @i as int,@count as int, @m as int,@j as int,@k as int
set @i=(select min(a.id) from ( select Begindate,Enddate,id
from  TBL_Hk_co_perprofile
where  len(Begindate)>10 and len(enddate)>10) a )--从查询结果中查

select @count=(select max(a.id) from ( select Begindate,Enddate,id from  TBL_Hk_co_perprofile where  len(Begindate)>10 and len(enddate)>10) a )
while @i<=@count
begin
   select @begin=replace((select begindate from( select Begindate,Enddate,id from  TBL_Hk_co_perprofile where  len(Begindate)>10 and len(enddate)>10) a  where id =@i)+',','N/A','0000-00-00')
   select @end=replace(( select Enddate from  ( select Begindate,Enddate,id from  TBL_Hk_co_perprofile where  len(Begindate)>10 and len(enddate)>10) a  where [ID]=@i )+',','N/A','9999-00-00')

   set @m =LEN(@begin)

  while  @m>0
     begin
     set @j=patindex('%,%',@begin)
     set @k=patindex('%,%',@end)
     set @a=substring(@begin,1,@j-1)--截取下一个逗号前的字符
     set @b=substring(@end,1,@k-1)

     if @a>@b
     begin
    select id,begindate,Enddate   from TBL_Hk_co_perprofile where id=@i
     end
     select @begin=substring(@begin,patindex('%,%',@begin)+1,len(@begin)-patindex('%,%',@begin))
     select @end=substring(@end,patindex('%,%',@end)+1,len(@end)-patindex('%,%',@end))

    select @m=LEN(@begin)
     end


  select @i=(select a.id
          from ( select Begindate,Enddate,id from  TBL_Hk_co_perprofile where  len(Begindate)>10 and len(enddate)>10) a
                 where a.id in (select top 1 a.id
                                  from ( select Begindate,Enddate,id from  TBL_Hk_co_perprofile where  len(Begindate)>10 and len(enddate)>10) a
                                  where id>@i
                                  order by id ))--查询下一条id

end

go