Hi,
i create n to n relations like this, right?
create table person ( id serial, name text
);
create table address ( id serial, street text ...
);
create table person2adress ( id serial, person_id integer not null references person(id), address_id integer
notnull references address(id),
);
than i can select all adresses from one person with id =1 with
select street
from address
where id = ( select adress_id from person2adress where person_id = 1 );
ok so far so good. but you can still insert persons without any
adress. so its a 0..n relation. But how van i achieve that you can´t
insert any person without adress???
thanks in advance
janning
