可更新视图(Oracle)

Question

可以说我们有以下内容:

create view view_1 as
(
  select key, data from some_table_or_view;
);

create table table_1
(
  key
  more_data
);

create view view_2 as
(
  select v1.key, v1.data, t1.more_data 
  from view_1 v1, table_1 t1 
  where v1.key = t1.key
);

create table table_2 as
(
  key
  data
  more_data
);

create view view_3 as
(
  select key, data, more_data from view_2
  union
  select key, data, more_data from table_2
);

基本上,我们加入了两个数据源,一个来自连接,一个是原始数据.

我希望能够做到以下几点.

update view_3 set more_data = 'BLAH_MORE_DATA' where key = 'BLAH_KEY';

以某种方式更新table_1或table_2取决于"BLAH_KEY"是否来自table_1或table_2.

目前我能想到的唯一方法是:

create view view_3 as
(
  select 'TAB1' as source, key, data, more_data from view_2
  union
  select 'TAB2' as source, key, data, more_data from table_2
);

然后使用PL/SQL函数进行更新,该函数检查源列并更新相应的表,但这意味着我必须保持视图和PL/SQL函数同步.

我正在寻找一种更好的方法来做到这一点.

Answer 1

您可以在view_3上使用而不是触发器

CREATE OR REPLACE TRIGGER view3_trg
INSTEAD OF  UPDATE
ON view_3
FOR EACH ROW
BEGIN
IF :OLD.source = 'TAB1' THEN

  UPDATE table_1 t1
  set t1.data = :NEW.data
  WHERE
    t1.key = :OLD.key
  ;
ELSIF OLD.source = 'TAB2' THEN
   UPDATE table_2 t2
  set t2.data = :NEW.data
  WHERE
    t2.key = :OLD.key
  ;
END IF;
END;
/