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postgresql - postgres trigger pass input to function

问题描述

I am trying to make a trigger that when a value is put into table1 it is then copied into table2. I have the following function which works correctly:

Create function func1(a integer) returns void
Language SQL as $$
insert into table2 values (a);$$;

and here is the trigger (it doesn't work):

Create trigger trig1
Before update on table1
For each row
Execute function func1(old.attr1)

I am trying to follow this documentation. Here is the part in particular I am following:

CREATE TRIGGER log_update
    AFTER UPDATE ON accounts
    FOR EACH ROW
    WHEN (OLD.* IS DISTINCT FROM NEW.*)
    EXECUTE PROCEDURE log_account_update();

I figured that old.attribute gives a particular attribute of the old row before it is changed. If I'm wrong on this let me know. Thanks

标签： postgresql

解决方案

文档说明了触发器中调用的函数：

用户提供的函数，声明为不带参数并返回类型触发器，当触发器触发时执行。

此函数可以访问OLD和NEW对象。您可以修改现有功能：

Create function func1()  RETURNS trigger
as $$
 BEGIN
   insert into table2 values (OLD.attr1);   
   RETURN NEW; 
 END;
$$  LANGUAGE plpgsql;

Create trigger trig1
  Before update on table1
  For each row
  Execute function func1();

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