A subset of a super key is considered a candidate key under which condition?

B. If no proper subset of it is a super key

A. If the subset itself can uniquely identify each tuple

B. If no proper subset of it is a super key

C. If it contains only a single attribute

D. If it is declared as a primary key

Computer · Database Management System · page 2 of 2

Database Keys MCQs with Answers

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11.
In MS Access, how many primary keys can a table have?
Correct Answer: A. 1
One-liner
In MS Access, a table can have only 1 primary key.
12.
In database management, what is the term used for a candidate key that is not chosen as the primary key?
Correct Answer: B. Alternate key
One-liner
A candidate key that is not selected as the primary key is called an Alternate key.
13.
What term describes a combination of one or more attributes used to uniquely identify a record in a database?
Correct Answer: B. Super key
One-liner
A super key is a set of one or more attributes that can uniquely identify each record in a database table.
14.
A subset of a super key is considered a candidate key under which condition?
Correct Answer: B. If no proper subset of it is a super key
One-liner
A candidate key is a super key whose no proper subset is a super key, meaning it is minimal and irreducibly unique.
15.
Which of the following is NOT suitable to use as a primary key in a database?
Correct Answer: C. Zip code
One-liner
Zip code is not suitable as a primary key because it is not unique — multiple people can share the same zip code.
16.
In database management, a composite key consists of how many attributes?
Correct Answer: B. More than one
One-liner
A composite key consists of more than one attribute to uniquely identify a record in a table.