Oracle自动增长的序列号

Create sequence user_id
Increment by 1
Start with 1
Maxvalue 1.0E28
Minvalue 1 nocycle
Cache 20
Noorder;

create or replace trigger AUTO_ID_ADD
before insert on userinfo
referencing old as old_value
new as new_value
for each row
begin
select USER_ID.nextval into :new_value.id from dual;
end;