On 10 Aug 2006 06:28:30 -0700,
Andrew Hammond <
andrew.george.hammond@gmail.com> wrote:
Tomski wrote:
> Hello!
> As many of you know, SQL Server (2000) has peculiar data type "timestamp"
> which is not SQL standard timestamp. In fact it is "rowversion" type. It
> makes tha field to be updated with current timestamp when row is updated or
> inserted.
> Is there any similiar functionality in PostgreSQL? If not, how to achieve
> that?
> I need such fields in many tables. Maybe triggers could help? Do I have to
> write functions for each trigger for each table? Or can it be done by one
> function with parameters? Partial or final solutions are welcome :)
Create your table with a column of type timestamp and DEFAULT (now())
and you have the on insert functionality. You need to use triggers to
get the on update fuctionality (and also for inserts if you don't trust
the application to leave it default). I think this is actually covered
by an example in the triggers documentation for postgres. If not then
there's certainly a full code solution in the archives of this list.
Please do some research before asking questions to the list.
I put a create_dt and modify_dt column on every table and set the default to now(). Then I use this trigger:
CREATE OR REPLACE FUNCTION "public"."modify_date_stamp_fn" () RETURNS SETOF opaque AS
'
BEGIN
-- if a trigger insert or update operation occurs
IF TG_OP = ''INSERT'' OR TG_OP = ''UPDATE'' THEN
-- assigns the current timestamp
-- into the mod_time column
NEW.modify_dt := now();
-- displays the new row on an insert/update
RETURN NEW;
END IF;
END;
'
LANGUAGE 'plpgsql' VOLATILE CALLED ON NULL INPUT SECURITY INVOKER;
CREATE TRIGGER "mytable_modify_dt_tr" BEFORE UPDATE
ON "public"."mytable" FOR EACH ROW
EXECUTE PROCEDURE "public"."modify_date_stamp_fn"();
==================================================================
Aaron Bono
Aranya Software Technologies, Inc.
http://www.aranya.com http://codeelixir.com==================================================================
