oracle - 仅触发更改的值

Question

假设我们在表中有 3 条记录:orig_tab

---------------------------------------------
|  PK  |  Name  |  Address  |  Postal Code  |
---------------------------------------------
|   1  |  AA    |  Street1  |   11111       |
|   2  |  BB    |  Street2  |   22222       |
|   3  |  CC    |  Street3  |   33333       |
---------------------------------------------

现在数据改变了:

---------------------------------------------
|  PK  |  Name  |  Address  |  Postal Code  |
---------------------------------------------
|   1  |  AA    |  Street1  |   11111       |
|   2  |  BB    |  Street2  |   44444       |
|   3  |  CC    |  Dtreet7  |   33333       |
---------------------------------------------

客户想要的是更新记录和更新的列(是的，我知道这没有任何意义，但他们使用 1970 年代的一些旧系统，他们想做一些日志记录等)。所以报表应该是这样的:

---------------------------------------------
|  PK  |  Name  |  Address  |  Postal Code  |
---------------------------------------------
|   2  |        |           |   44444       |
|   3  |        |  Dtreet7  |               |
---------------------------------------------

这是我尝试过的:

CREATE OR REPLACE TRIGGER vr_reporting_trigger
   AFTER UPDATE ON orig_tab
   FOR EACH ROW
BEGIN
IF inserting THEN
INSERT INTO rep_tab(pk, name, address, code)
  SELECT :new.pk, :new.name, :new.address, :new,code FROM DUAL
  WHERE NOT EXISTS (SELECT 1 FROM rep_tab WHERE pk = :new.pk);
UPDATE rep_tab t SET t.name = :new.name, t.address = :new.address, t.code = :new.code 
   WHERE t.pk = :new.pk;
ELSIF updating THEN
IF :new.pk <> :old.pk THEN
     UPDATE rep_tab t
        SET t.name = :new.name, t.address = :new.address, t.code =: new.code
      WHERE t.pk = :old.pk ;
  END IF;
  MERGE INTO rep_tab d
  USING DUAL ON (d.pk = :old.pk)
  WHEN MATCHED THEN
  UPDATE SET d.name = :new.name, d.address = :new.address, d.code =: new.code
  WHEN NOT MATCHED THEN
  INSERT (d.pk,d.name, d.address, d.code) VALUES (:new.pk,:new.name, new.address, new.code);
END IF;
END;

使用此解决方案，我得到:

---------------------------------------------
|  PK  |  Name  |  Address  |  Postal Code  |
---------------------------------------------
|   2  |  BB    |  Street2  |   44444       |
|   3  |  CC    |  Dtreet7  |   33333       |
---------------------------------------------

我知道它在更新语句时插入子句中的某个地方，但我无法弄清楚如何根据我的要求更改此子句。有什么建议吗？

提前致谢。

Answer 1

你需要这个:

In an UPDATE trigger, a column name can be specified with an UPDATING conditional predicate to determine if the named column is being updated. For example, assume a trigger is defined as the following:

CREATE OR REPLACE TRIGGER ...
... UPDATE OF Sal, Comm ON Emp_tab ...
BEGIN

... IF UPDATING ('SAL') THEN ... END IF;

END;

来自 Oracle documentation(9i)

11gR2 documentation