[LIP] which is the primary key

hi,
i have had occasion to interact with two rdbms gurus over the past 
week and they have challenged one of my most precious assumptions. 
Say we have two tables like so:

create table states
	(id	serial unique,
        name varchar(50)
	);
and
create table towns
	(
	id serial unique,
	name varchar(50)
	state integer references states(id)
	);

i put the name field as the primary key in each case, but they argue 
that the id key is to be the primary key. I always thought that the 
primary key was the one that uniquely defined a row. Of course, 
making the 'id' field the primary key would also uniquely define the 
row, but then the possibility arises of having rows that *only* 
differ in the 'id' field which doesnt sound like a good practice to 
me. This becomes more apparent when considering the case where the 
primary key has more than one field. 

comments anyone?
 
-- 
regards
kg

http://www.livejournal.com/users/lawgon
tally ho! http://avsap.org.in
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