---
title: "Discussion on \"DBMS Important Questions\" | Hashnode"
description: "Discussion on \"DBMS Important Questions\". What is the difference between primary key and unique constraints?The primary key cannot have NULL value, the unique constraints can have NULL values. There is only one primary key in a table, but there can be multiple unique constrains.\nWhat are the..."
url: "https://hashnode.com/posts/dbms-important-questions/66b81c28e17e3f6d1dbae161"
---

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# [DBMS Important Questions](https://shreshtxa.hashnode.dev/dbms-important-questions?utm_source=hashnode&utm_medium=feed)

What is the difference between primary key and unique constraints?The primary key cannot have NULL value, the unique constraints can have NULL values. There is only one primary key in a table, but there can be multiple unique constrains. What are the...

Aug 11, 2024 · 13 min read · shreshtxa.hashnode.dev  
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## Written by

[SHRESHTHA KUMAR GUPTA](https://hashnode.com/@shreshtxa)

@shreshtxa · Gurugram,India

  
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I love solving problems and talking about tech :)

Hey! I'm Shreshtha 👋 A builder at heart, curious about how things work under the hood. I love solving problems and turning ideas into real tech — from apps to APIs. This blog is where I share what I learn, what I break, and what I build — in real-time. No gatekeeping, just a fellow dev figuring things out and documenting the journey.

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