写法一:
select   *   from     [table1]   a   ,   (   select  key1,key2,key3,key4,key5,max(发生时间) as 发生时间 from table1 group by key1,key2,key3,key4,key5)   b     where   a.发生时间=b.发生时间   and   a.key1=b.key1 and a.key2=b.key2 and a.key3=b.key4 and a.key5=b.key5

写法二:

select   *   from     [table1]   a   where key1+key2+key3+key4+key5+convert(char(20),发生时间)  in    select  key1+key2+key3+key4+key5+convert(chart(20),max(发生时间))  from table1 group by key1,key2,key3,key4,key5