Re: Creating a trigger function

You want the TG_OP variable. For example:

IF TG_OP = 'INSERT' THEN
   .. code here ..
ELSIF TG_OP = 'UPDATE' THEN
   .. code here ..
ELSIF TG_OP = 'DELETE' THEN
   .. code here ..
END IF;

Greg

Peter Erickson wrote:

> Ok, I have determined that i can't do:
>   IF NEW IS NOT NULL  -- or -- IF OLD IS NOT NULL
> and that is what is causing the error.
>
> So, with this now known, is there a way to create a trigger & function
> that will allow inserts, updates, and deletes to occur while updating a
> field (mtime) in another table? At the same time, if an update takes
> place, it updates the modified time field (mtime) to the current time.
>
> I can them all to work individually by modifying the function, but I
> cant get the to all work in the same function. Do I need to create a
> trigger for inserts/updates and another for deletes?
>
> Any help is greatly appreciated. Thanks in advance.
>
> If it helps, here are the table definitions:
>
> CREATE TABLE journals (
>   id int NOT NULL DEFAULT nextval('journal_id_seq'::text),
>   owner_id int NOT NULL,
>   name varchar(15) NOT NULL,
>   descr varchar(50) NOT NULL,
>   ctime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6),
>   mtime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6),
>   CONSTRAINT journals_pkey PRIMARY KEY (id),
>   CONSTRAINT fkey_user_id FOREIGN KEY (owner_id) REFERENCES users
> (user_id) ON UPDATE CASCADE ON DELETE CASCADE,
>   CONSTRAINT journal_descr CHECK descr::text <> ''::text,
>   CONSTRAINT journal_name CHECK name::text <> ''::text
> );
>
> CREATE TABLE journal_entries
> (
>   id int NOT NULL DEFAULT nextval('journal_ent_id_seq'::text),
>   journ_id int NOT NULL,
>   entry varchar(1000) NOT NULL,
>   ctime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6),
>   mtime timestamp NOT NULL DEFAULT ('now'::text)::timestamp(6),
>   CONSTRAINT journal_entries_pkey PRIMARY KEY (id),
>   CONSTRAINT fkey_journal_id FOREIGN KEY (journ_id) REFERENCES journals
> (id) ON UPDATE NO ACTION ON DELETE NO ACTION,
>   CONSTRAINT entry_check CHECK entry::text <> ''::text
> );
>
>
> Peter Erickson wrote:
>
>> I am running postgresql 7.4.2 and having problems creating a trigger
>> function properly. I keep getting the following error:
>>
>> ERROR: OLD used in query that is not in rule
>>
>> I have a table called journal_entries with a foreign key to a table
>> called journals. When a entry is added to journal_entries, I am trying
>> to get it to update the 'mtime' field of the corresponding entry in
>> the journals table.
>>
>> Can anyone help me with this problem? If you need more information,
>> please let me know.
>>
>> CREATE OR REPLACE FUNCTION public.update_journal_mtime()
>>   RETURNS trigger AS
>> '
>>   DECLARE
>>     curtime TIMESTAMP;
>>   BEGIN
>>     curtime := \'now\';
>>     IF OLD IS NOT NULL THEN
>>       UPDATE journals SET mtime = curtime WHERE id = OLD.journ_id;
>>     END IF;
>>     IF NEW IS NOT NULL THEN
>>       UPDATE journals SET mtime = curtime WHERE id = NEW.journ_id;
>>       UPDATE journal_entries SET mtime = curtime WHERE id = NEW.id;
>>     END IF;
>>     RETURN null;
>>   END;
>> '
>>   LANGUAGE 'plpgsql' VOLATILE;
>>
>> CREATE TRIGGER update_mtime_trigger
>>   AFTER INSERT OR UPDATE OR DELETE
>>   ON public.journal_entries
>>   FOR EACH ROW
>>   EXECUTE PROCEDURE public.update_journal_mtime();
>
>
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