to:KingSunSha(弱水三千),刚才那个贴子已经给您结了，这儿还有一个触发器，总是编译错误，请再看一下。

CREATE OR REPLACE TRIGGER updatecustomername
before update on item
  REFERENCING OLD AS OLD NEW AS NEW
   FOR EACH ROW
   BEGIN
   if :NEW.customerid <> 0 then
  select customername
    into :NEW.customername
    from customer where customerid=:NEW.customerid;
    else
    NEW.customername='test';（这句如果是null就是好的）
    end if;
  end;
/
有编译错误，不知道为何