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,
from
port_activity as p
left outer join node as n
left outer join card as c
Best regards
Bèrto
On 10 December 2011 19:03, Richard Klingler
<richard@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
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