What are the differences between the terms, CANDIDATE KEY, PRIMARY KEY, SUPER KEY, COMPOSITE KEY?

Hi,
Can anybody tell me the differences between the above mentioned terms? Also please tell me if one can be the other and vice versa..please elaborate with the helpof a table if possible. Also please tellme if the below statement by me is correct..
a) Any attribute or a collection of attributes which uniquely identifies the tuples in a relation is called a canditate key.this candidate key thus can contain a single attribute or a collection of attributes.
b) one of the attributes is chosen by the DBMS to identify the tuples uniquely and this attribute is called the primary key. c) A primarykey is a candidate key.all candidate keys cannot be a primary key.
Now,,,what is the superkey? Received on Tue Feb 21 2006 - 05:45:59 CST