試題詳解

( )16.A key in DBMS is an attribute or set of attributes which helps you to identify a row(tuple) in a relation(table). Which of the following statements is NOT correct?
(A) A super key is a group of single or multiple keys which identifies rows in a table.
(B) A candidate key is a minimal super key or a super key with no redundant attribute.
(C) All the candidate key which are not a primary key are called an alternate key.
(D) The primary key is the minimal set of attributes which uniquely identifies any row of a table. Any super key can become a primary key.