具体步骤如下：

一、创建数据表
create table employee(
Id int ,
DeptNo number,
EmpNo number,
Ename varchar2(16),
Job varchar2(32),
Sal float,
HireDate date,
constraint pk_employee primary key(EmpNo)
);

二、创建员工表自动增长序列
create sequence employee_autoinc
minvalue 1
maxvalue 9999999999999999999999999999
start with 1
increment by 1
nocache;

三、创建触发器将序列中的值赋给插入employee表的行
create or replace trigger insert_employee_autoinc
before insert on employee
for each row
begin
select employee_autoinc.nextval into :new.Id from dual;
end insert_employee_autoinc;
/

四、验证
insert into employee(DeptNo,EmpNo,Ename,job,sal,hiredate) values(520,5201002,'James zhou','PD',6000,to_date('2012-10-22','yyyy-mm-dd'));
insert into employee(DeptNo,EmpNo,Ename,job,sal,hiredate) values(521,5211314,'xc','Boss',90000,sysdate);

五、结果截图