插入数据时，使用sequence为表自动生成主键
1.创建sequence
create sequence sequence_name
minvalue 1
maxvalue 99999999
start with 1
increment by 1
cache 20
2.建立触发器，使用sequence为表自动添加主键
create or replace trigger trg_insert_id
before insert on o_app_api
for each row
BEGIN
select sequence_name.nextval into :new.id from dual;
END;