Question

以下触发器已正确创建，并在UPDATE和INSERT语句之前触发。但是，在发出DELETE stmt时，它不显示任何内容。请帮助我在这里找到问题。

create or replace trigger tr_emp_saldiff
BEFORE INSERT OR UPDATE OR DELETE
ON emp
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
WHEN (new.emp_no > 0)
declare
    sal_diff number;
begin
    sal_diff  := :new.salary  - :old.salary;
    dbms_output.put(' Old salary: ' || :old.salary);
    dbms_output.put('  New salary: ' || :new.salary);
    dbms_output.put_line('  Difference ' || sal_diff);
END;
/

UPDATE emp set salary = salary + 500 where dept_no = 10;
Output :
1 row(s) updated.
Old salary: 20500 New salary: 21000 Difference 500

INSERT INTO EMP VALUES(1000,'Alice',15000,'Fiona',30);
Output :
1 row(s) inserted.
Old salary: New salary: 20000 Difference 

DELETE FROM emp where emp_name='Jane';
Output :
1 row(s) deleted.

在删除语句之后没有显示任何值。

Answer 1

WHEN (new.emp_no > 0)

对于DELETE不能成立，new.emp_no为null。

删除该条件或在DELETE上使用单独的触发器。（根据给出的信息，无论如何，UPDATE才有意义。INSERT或DELETE的薪水没有变化。）

在删除触发器未触发之前

1 个答案: