On Tuesday 19 August 2008, Gordon <gordon.mcvey@ntlworld.com> wrote:
> I want to be able to restrict any query that updates or deletes from
> the articles table so that they can only occur if there isn't a
> corresponding entry in the locks table. As far as I can tell,
> however, you can't join tables when doing updates or deletes. I know
> on the PHP side I can attempt to do a select on the locks table and
> only perform the delete if the select returns 0 rows, but I'd rather
> the update or delete query itself does the checking. Can anyone help
> out?
The best way to implement this is through triggers on the target tables.
However, you can also do joins with updates and deletes (UPDATE ... FROM and
DELETE ... USING).
--
Alan