随机读取数据--oracle

select * from ( select * from expert where name like '%%' order by dbms_random.random ) where rownum <= 10;

复合主键删除

1.先查出该联合主键的名字pk_all，如果已知，则省去此步骤，

select constraint_name  from user_constraints  where table_name=upper('tb1')  and constraint_type='P';

2.删除该主键

alter table tb1 drop constraint pk_all cascade;