oracle中创建自增长序列

首先创建序列：

create sequence incr_stu_id_seq
minvalue 1
start with 1
increment by 1

nomaxvalue
nocache;

然后创建触发器：

create or replace trigger incr_stu_id_trig
  before insert on students  
  for each row
begin
  select incr_stu_id_sequ.nextval into:new.id from dual;
end incr_stu_id_trig；

最后可以使用了：

insert into students(name,major,score) values('zhangsan','history',89);