> >> > -- c *= b *= a =* d =* f > >> > select * from a, outer( b, outer c), outer (d, outer f ) > >> > where a.b_id = b.id and b.c_id = c.id and a.d_id = d.id and d.f_id = f.id; > >> > >> from a full join b on (a.id=b.id) > >> full join c on (b.id=c.id) > >> full join d > >> > > > > I guess, you don't get it. Probably so > > I don't get it either. by *= do you mean the Oracle-style outer join? > in which case why is this not just > > select * from a, > left outer join b on (a.b_id = b.id) > left outer join c on (b.c_id = c.id) > left outer join d on (a.d_id = d.id) > left outer join f on (d.f_id = f.id) > The equal expression would be like this: select * from a left outer join (b left outer join c on (b.c_id = c.id) ) on (a.b_id = b.id) left outer join (d left outer join f on (d.f_id = f.id) ) on (a.d_id = d.id) and that is a double length of original SQL and has not very clear syntax in my opinion. Additionally it can be very funny if we try to append a join conditions like "c.iso = d.iso" > You can parenthesize it different ways but I think the result in this > case is actually the same. > I'm not sure. > > select * from a left outer join b on (a.b_id=b.id) .... > > > > But I don't see any clear way to specify that table C should be outer joined only if we got a row from table B. > > Well that would be the default since if you get no row from b b.c_id > will be null. > and if I have a row in table C where c.id is null? A don't know. I found a good explanation about informix outer joins. http://savage.net.au/SQL/outer-joins.html Please take a look at that. ________________________________________________________________ Neu: WEB.DE Doppel-FLAT mit Internet-Flatrate + Telefon-Flatrate für nur 19,99 Euro/mtl.!* http://produkte.web.de/go/02/ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
