我对创建trigger 语句中出现的referencing old as old new as new for each row不太理解,old 和new 各表示何意??
create or replace trigger bef_ins_t_country_define
before insert on t_country_define
referencing old as old new as new for each row
begin
select s_country_id.nextval into :new.country_id from dual;
end;
谁能帮我解释一下referencing old as old new as new for each row ???
我找了好几本sql 方面的书都没找到相关内容?