what is a candidate key

[dethfire]

can someone give me a good definition of what a candidate key is and how differs from a foriegn key? Also what is a superkey?

[MattR]

This is a good book which gives you a great founding in data management/DBMS fundamentals:
Practical Issues in Database Management

(that shouldn't have a referer link)

[r937]

while you are waiting for the book to arrive...

a candidate key is any column or combination of columns that uniquely identifies each row

a candidate key may therefore be the primary key ("candidate" -- get it?)

a foreign key, on the other hand, is a column that refers to the primary key of some (other) table

a superkey is found only in tables declared in the EssCue-Ell database on the planet krypton

all of the above except that last part are true

[dethfire]

what about this?

http://databases.about.com/cs/admini...g/superkey.htm

[r937]

hmmm, that sort of makes sense

first time i've heard of it, though

okay, well, let's put it a little more accurately -- i might have heard of it, but i don't remember hearing of it

it doesn't come up all that often

[MattR]

Edit:Ooops, I'm mistaken re: superkey. In any rate, SuperKey is probably not good terminology. I wouldn't use it.