Oracle触发器简单SQL

我正在尝试写这个触发器，但它不能正常工作。我有一张桌子给（捐助者，接收者，礼物名）和一个桌子人（姓名，年龄，头发颜色）。对于触发器，我希望它在捐助者和接收者具有相同的头发颜色时吐出消息。琐碎，我知道，但我刚刚开始学习触发器，并完全停留在为什么这不起作用。谢谢。Oracle触发器简单SQL

create or replace TRIGGER SameHairColor 
BEFORE INSERT OR UPDATE OF GIFTNAME ON GIVING 
DECLARE 
    haircolordonor varchar(255); 
    haircolorreceiver varchar(255); 
BEGIN 
select persons.haircolor into haircolordonor 
from persons, giving 
where (donor = persons.pname); 
select persons.haircolor into haircolorreceiver 
from persons, giving 
where (receiver = persons.pname); 

if (haircolordonor = haircolorreceiver) then 

dbms_output.put_line('Wow, they have the same haircolor! Who would have thought?'); 
end if; 

end;

该错误消息我得到的是错误的执行过程中“精确获取回报超过行的请求数量”，指着下面申报行...？

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2012-12-21 user1657563

您不限制您对查询插入/更新行的授权者/接受者。他们应该是这样的：

select persons.haircolor 
into haircolordonor 
from persons 
where persons.pname = :NEW.donor;

BTW：你只触发火灾上INSERT OR UPDATE OF GIFTNAME，而应该开枪INSERT OR UPDATE OF donor, receiver，你需要使用FOR EACH ROW。

你的触发器应该是这样的：

CREATE OR REPLACE TRIGGER SameHairColor 
BEFORE INSERT OR UPDATE OF donor, receiver ON GIVING 
    FOR EACH ROW 
DECLARE 
    haircolordonor varchar(255); 
    haircolorreceiver varchar(255); 
BEGIN 
    select persons.haircolor into haircolordonor 
    from persons 
    where (persons.pname = :NEW.donor); 
    select persons.haircolor into haircolorreceiver 
    from persons 
    where (persons.pname = :NEW.receiver); 

    IF (haircolordonor = haircolorreceiver) THEN 
    dbms_output.put_line('Wow, they have the same haircolor! Who would have thought?'); 
    END IF; 
END;

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2012-12-21 18:40:03

谢谢，这解决了我的问题，我可以运行插入，但我没有看到DBMS_output.put_line。我是一名运行oracle sql developer的新手，但我设置了服务器输出，我认为这可以解决我的问题？ – user1657563

您是否在SQL-Developer中激活“DBMS输出”？它是否显示你在不同的块中产生的消息，而不是触发器中的消息？ –

是启用，但不显示来自dbms_output.put_line的消息。 – user1657563

CREATE OR REPLACE TRIGGER SameHairColor 
BEFORE INSERT OR UPDATE OF GIFTNAME ON GIVING 
REFERENCING NEW ROW AS new 
FOR EACH ROW 
DECLARE 
    haircolordonor varchar(255); 
    haircolorreceiver varchar(255); 
BEGIN 
select persons.haircolor into haircolordonor 
from persons, giving 
where (:new.donor = persons.pname); 
select persons.haircolor into haircolorreceiver 
from persons, giving 
where (:new.receiver = persons.pname); 

if (haircolordonor = haircolorreceiver) then 
    dbms_output.put_line('Wow, they have the same haircolor! Who would have thought?'); 
end if; 

end;

或许这可能帮助？

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2012-12-21 18:43:00 span

是的，我试着让它为每行，但我仍然得到相同的错误消息。 – user1657563

您是否也使用“新”参考？ – span

它不会接受这种改变。无效的参考名称。 – user1657563

Oracle触发器简单SQL

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