if not exists(select 1 from tb) or (not exists select top 1 StartTime from tb order by id desc) insert 语句 if not exists (select top 1 id,PortId,StartTime,EndTime,Name,Mark from tb order by id desc) and exists(select top 1 path from tb order by id desc) update tb set path= 这样?
我想问一下,如果表的内容比较多的话(或者说很多)取最后一行通过order by desc 会不会影响效率,有没有其他的好的方法!
2、exists()判断
if not exists(select 1 from tb) or (not exists select top 1 StartTime from tb order by id desc)
insert 语句
if not exists (select top 1 id,PortId,StartTime,EndTime,Name,Mark from tb order by id desc)
and exists(select top 1 path from tb order by id desc)
update tb
set path=
这样?