急：sas取数与oracle取数的区别

shiyiming

select *
from
(
select rownum ro,a.*
from
(
select  distinct slab_no from ocx.dtis01 where rownum<=5  ) a
)
where ro>=2

data b (keep=slab_no);
set ocx.dtis01 (firstobs=1 obs=5);
run;
sas中的结果和plsql的结果数值相同但是顺序不同；
哪位高手能给我个合理的解释!