Re: Trigger Question - update a last_modified field

Thanks, worked beautifully. One more question: I've tried to find information on the useage of the host variables :new and :old. Although I have some vague understanding, what exactly do they mean, when do you use them (i.e., :new.last_modified - how does the :new relate to the row you're updating, and how does :old come into the picture).
Are their any others? Where can I find documentation on these?

Thanks.

In article <0Wwz7.60$%Z5.84_at_pollux.casema.net>, r.nospam.lascae_at_wanadoo.nl says...
> The first method may work, I didn't try it. The idea is correct: you don't
> update the table being modified in the trigger itself, rather you assign a
> value to the last_modified value in a before update trigger.
>
> The following works:
>
> CREATE OR REPLACE TRIGGER trigername
> before UPDATE
> on table_name
> for each row
> declare currtime date;
> begin
> currtime := SYSDATE;
> :new.last_modified := currtime;
> end;
> /
>
> HTH,
> Radu
> "John Harris" <John.Harris_at_nurs.utah.edu> wrote in message
> news:MPG.16383529b4a6fc74989680_at_news.cc.utah.edu...
> > I would like to create a row-level trigger for a table which occurs each
> > time the a row is updated. For instance, if any column changes then the
> > last_modified field gets updated with sysdate.
> >
> > Can I use something like (I know this isn't correct, but I haven't much
> > experience with this):
> >
> > begin
> > select sysdate into :new.last_modified from dual;
> > end;
> > or maybe something like
> > begin
> > update table set table.last_modified=sysdate;
> > end;
> >
> > Any help would be greatly appreciated.
> >
> > John Harris
>
>
>
Received on Thu Oct 18 2001 - 12:18:17 CDT