oracle随机取数据

select * from (select rownum,KEYWORD, CATEGORY,CREATE_DATE,UPDATE_DATE from 
(select * from knet_keyword_category_t where category='two') 
order by dbms_random.value) where  rownum<=10346;

select * from (select rownum,phone,create_time from tmp_Test order by dbms_random.value) where rownum<=50;