Обсуждение: query on multiple tables in schema

Hi, I wonder if anyone can help.

I'd like to execute a SQL query that performs an action on all the
(unrelated) tables that I select. The following query doesn't work, but
the subselect (which works) shows what I'm trying to do. All tables have
an identical column called id_num.

delete from
(select tablename from pg_tables where schemaname = 'public')
where id_num = null

I'd appreciate any advice.

On Tue, Sep 28, 2004 at 17:19:20 -0400,
  Angus Berry <angus.berry@elken.com> wrote:
> Hi, I wonder if anyone can help.
>
> I'd like to execute a SQL query that performs an action on all the
> (unrelated) tables that I select. The following query doesn't work, but
> the subselect (which works) shows what I'm trying to do. All tables have
> an identical column called id_num.
>
> delete from
> (select tablename from pg_tables where schemaname = 'public')
> where id_num = null

id_num = null will always return NULL which is not TRUE so that no rows
will be selected for deletion. Try using IS NULL instead.