---
title: "What is a \"primary key\"?"  
description: "What is a \"primary key\"?"  
author: "Pushpendra Singh"  
published: 2010-10-25  
updated: 2020-09-23  
canonical: https://www.mindstick.com/interview/91/what-is-a-primary-key  
category: "mssql server"  
tags: ["mssql server"]  
reading_time: 1 minute  

---

# What is a "primary key"?

Primary Key is a type of a constraint enforcing uniqueness and data integrity for each row of a table. All columns participating in a primary key constraint must possess the NOT NULL property.

## Answers

### Answer by Pushpendra Singh

Primary Key is a type of a constraint enforcing uniqueness and data integrity for each row of a table. All columns participating in a primary key constraint must possess the NOT NULL property.


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Original Source: https://www.mindstick.com/interview/91/what-is-a-primary-key

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