关于触发器

CREATE TRIGGER shuru ON [dbo].[线路巡视缺陷情况]
FOR INSERT
AS
declare @str char(8),@newfld char(12)
select @str=convert(char(8),getdate(),112)
select top 1 @newfld=编号 from 线路巡视缺陷情况 where 编号 like @str+'%' order by 编号 desc
if @newfld is null
  set @newfld=@str+'0001'
else
  set @newfld=@str+right(convert(char(5),10001+convert(int,right(@newfld,4))),4)
update 线路巡视缺陷情况 set   编号= @newfld