http://zhanghong.iteye.com/blog/865937
1. 首先创建数据库表
SQL> create table customer(
2 id number(8) not null primary key,
3 name varchar2(20),
4 age number(3),
5 gender varchar2(8)
6 );
2. 创建Sequence：
create sequence customer_SEQUENCE start with 6 increment by 1
3.创建Trigger:
create or replace trigger customer_trgger
before insert or update on customer
for each row
begin
select customer_SEQUENCE.nextval into :NEW.userID from dual;
end;
在插入数据的时候就不用提供id了。
SQL> insert into customer(name,age,gender) values('abc',33,'male');
1 row created.