Database - The Relational Model and Normalization - Discussion

Discussion :: The Relational Model and Normalization - General Questions (Q.No.5)

5. 

The primary key is selected from the:

[A]. composite keys.
[B]. determinants.
[C]. candidate keys.
[D]. foreign keys.

Answer: Option C

Explanation:

No answer description available for this question.

Uday Kiran said: (Nov 16, 2010)  
A primary key is taken from the Superkey, which is the set of candidate keys and other attributes. And the attributes other than.

Candidate key is not possible, so primary key is selected from candidate keys.

Raku said: (Dec 30, 2011)  
Composite keys consist of set keys.

Suraj R. said: (Jan 17, 2012)  
Candidate key is a set of keys or attributes of an entity which are eligible to be a primary key at some time.

Jyoti said: (Feb 8, 2012)  
Practically candidate key has no appearance in database so we choose primary keys from candidate keys for the practical implementation.

Sanjib said: (Feb 14, 2012)  
Minimum super key called composit key.

But what is candidate key?

Pooja Manoja said: (Feb 19, 2012)  
There may be more than one attributes in a relation, which recognizes a tuple uniquely. (each of attributes have a property of primary key) these attributes are called candidate day.

For example :in a student relation sid and regd are primary key.

Madhur said: (Oct 4, 2013)  
One of the candidate key is called primary key.

Sathish said: (Feb 1, 2014)  
Only one key existence for a relation called candidate key that will become the primary key that will never reducible.

Sathi said: (Mar 6, 2014)  
One of the minimal candidate key that derives all attributes of a relation.

Suchismitam said: (Jun 4, 2014)  
Candidate key contains no.of attributes which are the candidate to be the primary key (must contain unique value, must not be null). The keys other than primary key is known as non-prime key.

Rahul said: (Oct 14, 2014)  
Guys. Does candidate or unique key has got the same property or features of Primary key?

Lovepreet said: (Feb 26, 2015)  
One table contain multiple candidate key by single primary key.

Karthik said: (Apr 23, 2015)  
Candidate key is a combination of two or more attributes (emp name, emp street), from which primary key will be derived, primary key derived from set of candidate keys.

Siddhu said: (Aug 25, 2015)  
A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table.

Each Candidate Key can qualify as Primary Key. Primary Key " A Primary Key is a column or a combination of columns that uniquely identify a record.

Elias Joseph said: (Jul 3, 2017)  
Minimum super key is called candidate key so primary key is the part of the candidate key.

Post your comments here:

Name *:

Email   : (optional)

» Your comments will be displayed only after manual approval.