oracle 的rownum

select awmid,yxjstpath,to_char(awmtime,'yyyy-mm-dd') as awmtime,awmaddress,hostempname,joinnum 

from (select t.awmid,t.yxjstpath,t.awmtime,t.awmaddress,t.hostempname,t.joinnum from 

b_r_assignworkmeeting t  where  t.yxjstpath is not null and t.deptid =" + deptid + "

order by t.recorddate desc ,t.awmid desc )  where rownum<=10

select t.awmid,t.yxjstpath,t.awmtime,t.awmaddress,t.hostempname,t.joinnum from  b_r_assignworkmeeting t 

where  rownum<=10 and t.yxjstpath is not null and t.deptid =" + deptid + "order by t.recorddate desc ,t.awmid desc

两种查询结果在某种情况下，查询结果不一样， 第一种查询最新10条是正确的。oracle的bug