随机取 数据库中的 记录

--从一个表中随机取两条记录 --1.dbms_random.value select * from(select * from t_ums_config order by dbms_random.value) where rownum <= 2; --2.dbms_random.random select * from(select * from t_ums_config order by dbms_random.random) where rownum <= 2; --3.sys_guid() select * from(select * from t_ums_config order by sys_guid()) where rownum <= 2; --4.sample(20) 按百分比 select * from(select * from t_ums_config sample(20)) where rownum <= 2; --5.sample block(20) 按数据块 select * from(select * from t_ums_config sample block(40)) where rownum <= 2;