使用编译错误创建触发器

Question

我正在尝试创建一个触发器，每次客户下订单时，都会将客户的盘旋增加.04。接下来我需要在订单表中插入新订单。

以下是客户表：

CID  CNAME         CITY                     DISCNT
c001 Tiptop        Duluth                       10
c002 Basics        California                   12
c003 7/11          California                    8
c004 ACME          Duluth                        8
c006 ACME          Kyoto                         0
c007 Goldberg      NYC                          15

以下是订单表：

 ORDNO MON CID  AID PID        QTY    DOLLARS
  1011 jan c001 a01 p01       1000        450
  1012 jan c001 a01 p01       1000        450
  1019 feb c001 a02 p02        400        180
  1017 feb c001 a06 p03      95959        540
  1018 feb c001 a03 p04        600        540
  1023 mar c001 a04 p05        500        450
  1022 mar c001 a05 p06        400        720
  1025 apr c001 a05 p07        800        720
  1013 jan c002 a03 p03       1000        880
  1026 may c002 a05 p03        800        704
  1015 jan c003 a03 p05       1200       1104
  1014 jan c003 a03 p05       1200       1104
  1021 feb c004 a06 p01       1000        460
  1016 jan c006 a01 p01       1000        500
  1020 feb c006 a03 p07        600        600
  1024 mar c006 a06 p01        800        400

我创建的触发器是：

create or replace trigger UpdateDiscnt
after insert or update on orders   
  for each row
  begin 
     update customers set  discnt = 0.4 + :old.discnt where 
     customers.cid=:new.cid;
  end;
   /

Answer 1

错误是oracle错误，订单表中没有discnt，因此任何版本的old.discnt都不正确。

尝试

create or replace trigger UpdateDiscnt
after insert or update on orders   
  for each row
  begin 
     update customers set  discnt = 0.4 + discnt 
     where  customers.cid= :new.cid;         

  end;
   /