Oracle PL / SQL：动态循环触发器列 [英] Oracle PL/SQL: Loop Over Trigger Columns Dynamically

问题描述

在触发器内部，我试图循环一个表上的所有列，并将新值与旧值进行比较。这是我到目前为止：

Inside of a trigger I'm trying to loop over all columns on a table and compare the new values to the old values. Here is what I have so far:

CREATE OR REPLACE TRIGGER "JOSH".TEST#UPD BEFORE 
UPDATE ON "JOSH"."TEST_TRIGGER_TABLE" REFERENCING OLD AS OLD NEW AS NEW FOR EACH ROW
declare    
   oldval varchar(2000);   
   newval varchar(2000);   
begin    
   for row in (SELECT column_name from user_tab_columns where table_name='TEST_TRIGGER_TABLE') loop  
     execute immediate 'select :old.'||row.column_name||' from dual'   into oldval;  
     execute immediate 'select :new.'||row.column_name||' from dual'   into newval;  
     --Do something here with the old and new values
   end loop;  
end;

触发器编译，但触发器触发时，我得到：

The trigger compiles, but when the trigger fires, I'm getting:

ORA-01008：并非所有变量绑定

ORA-01008: not all variables bound

执行立即，因为它期待一个值：old 。 ：旧的和：新的已经被定义为触发器的一部分，但似乎执行立即无法看到这些变量。

on the first execute immediate because it's expecting a value for :old. :old and :new are already defined as part of the trigger, but it appears that execute immediate can't see those variables.

有没有办法动态地迭代触发器中的列值？

Is there a way to dynamically iterate over the column values in a trigger?

推荐答案

不，您不能动态地引用：old和：新值。正如Shane所说，您可以编写代码来生成静态触发器代码，如果这使得生活更轻松。此外，您可以将做某事放入程序包中，以使您的触发器变为：

No, you cannot reference :old and :new values dynamically. As Shane suggests, you can write code to generate the static trigger code, if that makes life easier. Also, you can make "do something here" into a package procedure so that your trigger becomes:

CREATE OR REPLACE TRIGGER JOSH.TEST#UPD BEFORE 
UPDATE ON JOSH.TEST_TRIGGER_TABLE
begin    
   my_package.do_something_with (:old.col1, :new.col1);
   my_package.do_something_with (:old.col2, :new.col2);
   my_package.do_something_with (:old.col3, :new.col3);
   -- etc.
end;

（您可以通过这种方式来剔除无意义的REFERENCING子句）。

(You can ditch the pointless REFERENCING clause by the way).

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