oracle主键自增

1.创建表

create table Test_Increase(
           userid number(10) primary key,  /*主键，自动增加*/
           username varchar2(20)
           );

 2.创建序列

CREATE SEQUENCE TestIncrease_Sequence
 INCREMENT BY 1   -- 每次加几个  
     START WITH 1     -- 从1开始计数  
     NOMAXVALUE       -- 不设置最大值  
     NOCYCLE          -- 一直累加，不循环  
     CACHE 10; 

 3. 创建触发器

CREATE TRIGGER Test_Increase BEFORE
insert ON  Test_Increase FOR EACH ROW
begin
select TestIncrease_Sequence.nextval into:New.userid from dual;

end;

 4.提交

commit;

 5.测试

insert into Test_Increase(Username) values('test')