oracle 創建遞增觸發器

--1.創建表
create table tb_users
 (
  id number(4),
  userName varchar2(20),
  password varchar2(20)
 )
--2.創建序列
create sequence sq_user
 start with 1
 increment by 1
--3.創建觸發器     
create or replace trigger tri_tb_users       
before insert on tb_users       
for each row       
begin       
select sq_user.nextval into :new.id from dual;      
end ;   
--4.添加數據
 begin
 insert into tb_users(username,password) values('xiachufeng','xiachufeng');
 insert into tb_users(username,password) values('Kevin','Kevin');
 commit;
 end;
--5.查詢數據  發現id列是遞增的
 select * from tb_users