Oracle数据库自动增长列的实现过程:

◆1.创建序列

-- Create sequence 
create sequence INNERID
minvalue 1
maxvalue 99999999999999
start with 1
increment by 1
cache 20
order;

◆2.--INNERID.currval 指当前序列

--INNERID.nextval 指下一个序列

create table admin
(id varchar2(20),name varchar2(10));
insert into admin values (INNERID.nextval,'a');
insert into admin values (INNERID.nextval,'b');
insert into admin values (INNERID.nextval,'c');
insert into admin values (INNERID.nextval,'d');

--不断的插入序列的下一个值.



◆3.创建触发器(注:此处无法设置id的默认值为INNERID.nextval )

CREATE OR REPLACE TRIGGER admin_tg
--admin id 的触发器
BEFORE INSERT ON admin FOR EACH ROW
BEGIN
SELECT INNERID.NEXTVAL INTO :NEW.id FROM DUAL;
END;

insert into admin (username) values ( 'zdz');