oracle逐渐自增长例子
//例如表结构
crete table t_user(id varchar2(20),name varchar2
(100),add varchar2(200));

//创建序列
create sequence t_user_ID
minvalue 1
maxvalue 100000
start with 1
increment by 1

2.触发器代码改为
create or replace trigger t_user_dml_tgr
before insert
on t_user
    for each row
declare
primary_key_value varchar(10);
begin
     select t_user_id.nextval into primary_key_value

from dual;
     :new.id:=primary_key_value;
end;