oracle 自增长

1、在scott用户下建立表dept
create table DEPT
(
  DEPTNO NUMBER(2) not null,
  DNAME VARCHAR2(14),
  LOC VARCHAR2(13)
)

2、建立一个sequence
create sequence seq_dept
minvalue 1
start with 1
increment by 1
nocache;

3、为dept表建立一个insert trigger
create or replace trigger insert_dept
  before insert on dept  
  for each row
declare
  -- local variables here
begin
   select seq_dept.nextval into :new.deptno from dual;
end insert_dept;

4、用insert语句测试

insert into dept(dname,loc) values('aaaaaa','bbbbb');