I guess this is what you mean: create table node( id bigint primary key); insert into node values (1); insert into node values (2);
create table card( id integer primary key); insert into card values (1); insert into card values (2); create table port_activity ( portid integer primary key, port2node bigint, port2card integer ); alter table port_activity add constraint myconst1 foreign key (port2node) references node (id); alter table port_activity add constraint myconst2 foreign key (port2card) references card (id); insert into port_activity values (1,1,NULL); insert into port_activity values (2,NULL,1); select p.portid as port, coalesce(n.id,c.id) as destination from port_activity as p left outer join node as n on p.port2node=n.id left outer join card as c on p.port2card=c.id; Best regards Bèrto On 10 December 2011 19:03, Richard Klingler <rich...@klingler.net> wrote: > Good day... > > I'm trying to build a query for PGSQL 9.1 where a table has two > references with only one being used depending of the type of entry.. > > For example, the table has following simplified structure: > > portid primary key > port2node index to table node > port2card index to table card > > So how can I do a conditional FROM clause in the query depending on the > column port2node and port2card? > If port2card is Null or 0 I don't want it in the FROM clause as the > query will return unneccessary duplicate > row...the same goes for port2node being Null or 0... > > > thanx in advance > richard > > > -- > Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-sql > -- ============================== If Pac-Man had affected us as kids, we'd all be running around in a darkened room munching pills and listening to repetitive music.
