What is a candidate key in DBMS?/ What is a candidate key explain with example?

Hello Friends, In this blog post we are going to discuss what is a candidate key in DBMS. An attribute or a column in a table that can identify a full tuple or row records in a data table is considered as a candidate key.

Now the question is that all the other keys like primary, alternate, super, unique, foreign also used to uniquely identify a tuple value so are they all a candidate key?

Yes, any key that is capable to identify a tuple value is considered as a candidate key though they could also have their own features like a primary key does not allow to enter a null value. Whereas a unique key allows doing the same.

Within this blog, we will see what is candidate key explains with an example? What is the candidate key and primary key? What is the use of the candidate key? What is the difference between the super key and the candidate key?…

… Candidate key vs primary key, Super key and candidate key, Candidate key example, What is Super key, Alternate key, Super key example.

What is the candidate key and primary key?

Both keys can uniquely identify the tuple value or full records. The primary key also a candidate key. But the primary key is a candidate key with no null value. and in a single table, there could be only one primary key.

Candidate key may hold the null value. And in a single database table there could be more than one candidate key.

What is the use of the candidate key?

The purpose of the candidate key is to select the primary key from the set of all candidate keys. There must be one candidate key in the table that could be considered as the primary key of the table to uniquely identify the records.

What is the difference between the super key and candidate key?

Candidate keys are the subset of the super keys. All candidate key is super keys but all super keys may or may not the candidate keys. The candidate key is the minimal set of attributes to uniquely identify the tuple value. Where the super key is the set of one or more columns or attributes to uniquely identify the tuple value.

What is the candidate key explain with example?

With the help of below image you can understand the whole scenario of all the keys.

candidatekey-in-dbms-img
DBMS-KEYS-CANDIDATE KEY

In a very simple language, we can say that a candidate key is a generalized concept to have unique value to identify the whole row record. thus any DBMS key fulfilling this criterion will be a candidate key.

Conclusion:

Every key that can easily identify a tuple value with the property of uniqueness, mean to say that every tuple has a unique value for a particular attribute value is called a candidate key. There may be one and more candidate keys in the database table.

Using this blog we have explored Candidate key vs primary key, Super key and candidate key, Candidate key example
What is Super key, Alternate key, Super key example?.

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Anurag

I am a blogger by passion, a software engineer by profession, a singer by consideration and rest of things that I do is for my destination.