Question

我想制作触发器，它会计算不同表格的价格。

看起来像这样：

PART_PRICE(from PARTS) + TIME(from PARTS) * SALARY_PER_HOUR(from MECHANIC)

并且结果应该保存在PRICE（来自预订），表格保留包含连接到PARTS＆amp;的表格ID_PART和ID_MECHANIC。力学。

我真的不知道该怎么做，你能帮助我吗？

Answer 1

首先应该在DDL语句上触发触发器。从问题中不清楚您想要触发哪个表更改。根据您的问题，如果ID_PART或ID_MECHANIC有任何更改，我认为您要更新预订表的价格栏。请找到以下代码。

CREATE TRIGGER trgAfterUpdate AFTER UPDATE ON RESERVATIONS 
FOR EACH ROW
AS
    declare part_id int;
    declare mechanic_id int;
    declare time long;
    declare part_price decimal(10,2);
    declare mechanic_sal decimal(10,2); 

    if NEW.ID_PART <> OLD.ID_PART 
        part_price = select PART_PRICE from parts where id_part=new.id_part;
        time = select TIME from parts where id_part=new.id_part;
        mechanic_sal = select SALARY_PER_HOUR from mechanic where id_mechanic=old.id_mechanic;
        update RESERVATIONS set PRICE = part_price+time*mechanic_sal where ID_PART=NEW.ID_PART and ID_MECHANIC=OLD.id_mechanic;
    else if NEW.ID_MECHANIC <> OLD.ID_MECHANIC
        part_price = select PART_PRICE from parts where id_part=old.id_part;
        time = select TIME from parts where id_part=old.id_part;
        mechanic_sal = select SALARY_PER_HOUR from mechanic where id_mechanic=new.id_mechanic;
        update RESERVATIONS set PRICE = part_price+time*mechanic_sal where ID_PART=OLD.ID_PART and ID_MECHANIC=NEW.id_mechanic;
GO

Oracle触发器连接到不同的表

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