Re: join in SQL

Hi,
You need an outer join to do this.
Any time B is empty, you got "no rows .."

Try somewhat as

    select a.value AV, c.value, AC from a, c

    where (       (a.c_id = c.id)
                 OR exists (select 'X' from b
                                    where (b.c_id = c.id and b.a_id = a.id))

this method inhibit action of B in the first request and don't require A & C in the subquery.

HTH :-)

--
REIP Jean-Claude
Enlevez ".remove.this" de l'adresse (anti-spam)
jacari.consultant.remove.this_at_skynet.be
Gerard Le Comte wrote in message <346182F1.1700_at_sns.fr>...


>

>Consider now, that I want to know all group (a.value;c.value)

>and that B is empty.

>

>----

>select a.value AV, c.value, AC from a, b, c

>where

>((a.c_id = c.id)

> OR (b.c_id = c.id and b.a_id = a.id)

>);

>----

>

>the result is always "no row selected" even if this

>request don't return "no row.." :