What is the use of a primary key?

Hi,

I've got the following doubt: why is necessary to define a primary key?. I mean, the candidate keys must be defined as not null and unique (just the same that with the primary key), so... what's the difference?. Why is it necessary to consider a primary key instead of simply defining a set of candidate keys?.

Thanks Received on Wed Nov 20 2002 - 17:44:13 CST