---
title: "Difference between Primary Key and Unique Key."  
description: "Difference between Primary Key and Unique Key."  
author: "Anonymous User"  
published: 2010-10-20  
updated: 2020-09-18  
canonical: https://www.mindstick.com/interview/62/difference-between-primary-key-and-unique-key  
category: "mssql server"  
tags: ["mssql server"]  
reading_time: 1 minute  

---

# Difference between Primary Key and Unique Key.

**Primary Key:** A column in a table whose values uniquely identify the rows in the table. A primary key value cannot be NULL. \
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**Unique Key:** Unique Keys are used to uniquely identify each row in an Oracle table. There can be one and only one row for each unique key value.

## Answers

### Answer by Rajesh Goswami

**Primary Key:** A column in a table whose values uniquely identify the rows in the table. A primary key value cannot be NULL. \
\
**Unique Key:** Unique Keys are used to uniquely identify each row in an Oracle table. There can be one and only one row for each unique key value.


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