Reference to multiple cols

Hi!

I want to make a table with a column that references to multiple tables. Is
that possible? Look at the 3rd row:

1. create table dog(barking_volume int,slobber_amount int);
2. create table cat(laziness int);
3. create table animals(name text,ref_animal oid references cat(oid) and
dog(oid) );

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I want to use references to ensure that i can not delete a row from dog or
cat tables if it is referenced from animals-table.

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Also I could reference straight to the general oid-value but I think it
isn't possible either - like:

create table animals(name text,ref_animal oid references <alltables>.oid);

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i and my cat Naukki (laziness == 98) will be glad for any help.

ville jungman, ulvilantie 3 b 11, 00350 helsinki, finland
tel. + 358 - 9 - 225 4482 , http://www.kolumbus.fi/vilmak
usko Herraan Jeesukseen, niin sin pelastut. (apt. 16:31)

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