Question

这是一个家庭作业问题。 customer表包括：customer_num，customer_name，street，city，state，postal_code，balance，credit_limit，rep_num。该表将通过rep_num链接到rep表，并通过customer_num链接到orders表。我在customer表中插入了一行，因此我不会删除实际数据，所以插入行的代码是：

insert into customer
    values('217','Big Bird','123 Sesame
    Street','Pittsburgh','PA','15301',1.00,100.00,'15');

然后我将服务器输出设置为：

set serveroutput on;

这是我的代码，它让我拒绝，＆＃34;警告：使用编译错误创建的触发器。＆＃34;：

create or replace trigger print_customer_deleted
after delete on customer for each row
begin
delete customer_num
set on customer = on.customer - new.customer_num
where customer_num = :new.customer_num;

dbms_output.put_line('Customer number '||customer_num||
                    ' is deleted');
end;
/

另外，这是我的触发器执行的方式吗？：

accept item_num prompt 'Enter customer number to be deleted: ';

execute print_customer_deleted('&customer_num');

Answer 1

我已经根据Scott的DEPT创建了一个TEST表。触发（在DEPT上删除后）从TEST中删除一行并显示一条消息。

SQL> select * From dept;

    DEPTNO DNAME          LOC
---------- -------------- -------------
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON

SQL> create table test as select * From dept;

Table created.

SQL> create or replace trigger trg_ad_dept
  2    after delete on dept
  3    for each row
  4  begin
  5    delete from test
  6      where deptno = :old.deptno;
  7
  8    dbms_output.put_line('Department #' || :old.deptno ||' is deleted');
  9  end;
 10  /

Trigger created.

让我们看看它是如何运作的：

SQL> delete from dept where deptno = 30;
Department #30 is deleted

1 row deleted.

SQL> select * From dept;

    DEPTNO DNAME          LOC
---------- -------------- -------------
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        40 OPERATIONS     BOSTON

SQL> select * From test;

    DEPTNO DNAME          LOC
---------- -------------- -------------
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        40 OPERATIONS     BOSTON

SQL>

似乎没问题 - 部门＃30已从两个表格中删除了消息已显示。

将它应用到您的情况（我没有您的表，并且您没有提供测试用例）。

在删除客户上创建一个显示消息的触发器，＆＃34;删除客户编号217＆＃34;

1 个答案: