设置如下：
sql>create table articletype(id number primary key,name varchar2(30));
sql>create sequence seq_aritcle_id increment by 1 start with 1 maxvalue 999999999;
sql>create trigger trg_articletype_id
    before insert
    on articletype
    for each row
    begin
    select seq_articletype_id.nextval into :new.id
    from dual;
    end;
    /