Re: Referencing external table in update/insert triggers

On Thu, Feb 18, 2010 at 2:53 PM, Richard Huxton <dev(at)archonet(dot)com> wrote:

> On 17/02/10 15:18, Amitabh Kant wrote:
>
>>
>> CREATE OR REPLACE FUNCTION update_data() RETURNS TRIGGER AS $update_data$
>> BEGIN
>> IF NEW.t1f4> t2.t2f4
>> UPDATE t2 set t2f2=NEW.t1f2, t2f3=NEW.t1f3, t2f4=NEW.t1f4 where
>> t2f1=NEW.d1;
>> RETURN NEW;
>> END IF;
>> END;
>> $update_data$ LANGUAGE plpgsql;
>>
>
> I would like to compare the date present in the t2f4 with the new data
>> being
>> updated through the trigger. Using the if line as listed above returns an
>> error.
>>
>
> You can always do something like:
> SELECT t2.t2f4 INTO my_variable FROM t2 WHERE ...
> IF NEW.t1f4 > my_variable
>
> However, for this case you can just do an update with an extended where
> clause:
> UPDATE t2 ... WHERE t2f1=NEW.d1 AND NEW.t1f4 > t2.t2f4
>
> No need for the IF.
>
> --
> Richard Huxton
> Archonet Ltd
>

Thanks Richard.

With regards

Amitabh Kant