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，但他们使用的是 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;

通过这个解决方案，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处，但我不知道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：

在 UPDATE 触发器中，可以使用 UPDATING 指定列名 条件谓词来确定命名列是否正在 更新。例如，假设触发器定义如下：

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

Answer 2

仅触发更改的值。

作为一个例子（仅NOT NULL 支持）（带有 NULL 的比较运算符总是返回 FALSE）：

CREATE OR REPLACE TRIGGER trigger_department_update
  BEFORE UPDATE OF 
      department_id,
      cluster_id, 
      division_id, 
      macroregion_id, 
      address, 
      email
    ON cl_department
  FOR EACH ROW
BEGIN
  IF (
    :new.department_id != :old.department_id
    OR :new.cluster_id != :old.cluster_id
    OR :new.division_id != :old.division_id
    OR :new.macroregion_id != :old.macroregion_id
    OR :new.address != :old.address
    OR :new.email != :old.email
  ) 
    THEN :new.update_date := CURRENT_TIMESTAMP; 
  END IF;
END;

支持 NULL（感谢本文下方 cmets 中的@Oleg）（感谢@Chris Bandy 提供answer）：

CREATE OR REPLACE TRIGGER trigger_department_update
  BEFORE UPDATE OF 
      department_id,
      cluster_id, 
      division_id, 
      macroregion_id, 
      address, 
      email
    ON cl_department
  FOR EACH ROW
BEGIN
  IF (
    ((:new.department_id <> :old.department_id OR :new.department_id IS NULL OR :old.department_id IS NULL) AND NOT (:new.department_id IS NULL AND :old.department_id IS NULL))
    OR ((:new.cluster_id <> :old.cluster_id OR :new.cluster_id IS NULL OR :old.cluster_id IS NULL) AND NOT (:new.cluster_id IS NULL AND :old.cluster_id IS NULL))
    OR ((:new.division_id <> :old.division_id OR :new.division_id IS NULL OR :old.division_id IS NULL) AND NOT (:new.division_id IS NULL AND :old.division_id IS NULL))
    OR ((:new.macroregion_id <> :old.macroregion_id OR :new.macroregion_id IS NULL OR :old.macroregion_id IS NULL) AND NOT (:new.macroregion_id IS NULL AND :old.macroregion_id IS NULL))
    OR ((:new.address <> :old.address OR :new.address IS NULL OR :old.address IS NULL) AND NOT (:new.address IS NULL AND :old.address IS NULL))
    OR ((:new.email <> :old.email OR :new.email IS NULL OR :old.email IS NULL) AND NOT (:new.email IS NULL AND :old.email IS NULL))
  ) 
    THEN :new.update_date := CURRENT_TIMESTAMP; 
  END IF;
END;

Answer 3

对待 null ：

... nvl(to_char(:new.department_id,' ') <> nvl(to_char(:old.department_id,' ') OR ...