What is a Candidate Key?
A candidate key is a minimal set of attributes that uniquely identifies each tuple within a table. In other words, there should not be any two rows in a table that can have the same values for the columns that are the part of candidate key. It is very important for establishing relationships between tables and maintaining data integrity. Candidate keys play a pivotal role in database normalization as they help us to eliminate data redundancy and anomalies.
Example of Candidate Key
Let’s try to understand, the concept of the candidate key with an example of a student table.
|
Student_id |
Roll_no |
Name |
Mobile_no |
Email_id |
|---|---|---|---|---|
|
A1 |
1 |
Dipak |
9120 |
a@gmail.cpm |
|
A2 |
2 |
Raja |
8732 |
b@gmail.com |
|
A3 |
3 |
Dipak |
8344 |
c@gmail.com |
In this table, each student can uniquely identify by any of the following attribute: Student_id, Roll_no, Mobile_no, Email_id. So let primary key is Student_id and Candidate keys are Student_id, Roll_no, Mobile_no, Email_id.
Candidate Key in DBMS
Candidate keys play an essential role in Database Management Systems (DBMS) by ensuring data integrity and efficient retrieval. A candidate key refers to a set of attributes that can uniquely identify each record in a table. In this article, we will explore the concept of candidate keys, their significance in DBMS, and their crucial role in optimizing databases.