---
title: "What is a primary key?"  
description: "What is a primary key?"  
author: "Anonymous User"  
published: 2019-04-06  
updated: 2020-09-16  
canonical: https://www.mindstick.com/interview/23500/what-is-a-primary-key  
category: "database"  
tags: ["database", "sql server"]  
reading_time: 1 minute  

---

# What is a primary key?

The **primary key** is a combination of fields which uniquely specify a row. This is a special kind of unique key and it has an implicit, **NOT NULL** constraint. This means Primary key values cannot be NULL.

## Answers

### Answer by Anonymous User

The **primary key** is a combination of fields which uniquely specify a row. This is a special kind of unique key and it has an implicit, **NOT NULL** constraint. This means Primary key values cannot be NULL.


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Original Source: https://www.mindstick.com/interview/23500/what-is-a-primary-key

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