1.随机从某张表取某一字段值：
select id
from (
select id
from table
order by dbms_random.value)
where rownum=1
2.随机获取1-5（不包含5）中的整数：
select trunc(dbms_random.value(1, 5)) from dual;
3.随机生成年月日，时分秒：
select TO_CHAR(to_date(to_number(to_char(trunc(sysdate, 'year'), 'J')) +
trunc(DBMS_RANDOM.VALUE(0, 365)),'J') +
(TRUNC(DBMS_RANDOM.VALUE(9, 17)) * 3600 +
TRUNC(DBMS_RANDOM.VALUE(0, 60)) * 60 +
TRUNC(DBMS_RANDOM.VALUE(0, 60))) / (24 * 60 * 60),'yyyyMMdd') from dual;