DB Candidate Keys

apr911

Hey all,

Im having a bit of difficult understanding candidate keys that Im hoping someone might be able to help explain it. Id ask the DBA's at work but they wont be in until Monday and Im hoping to get through this material before than which means I need to understand them but cant wait till monday.

So the problem Im having is with the lifetime of a candidate key. I think I pretty well understand that the candidate key is exactly as it sounds, a candidate attribute for use as a primary key.

Where Im struggling is with the lifetime. At what point during Database design and/or utilization does the candidate key die?

I would have thought that once you choose the primary key (either in the conceptual or logical design phase), the need for candidate keys goes away yet the book im reading for database design continues to reference candidate keys side-by-side to chosen primary keys...

Which is confusing the h**l out of me.