8- Primary Key vs Unique Key in SQL | Differences and How to Use Them | SQL Tutorial

Title:
Primary Key vs Unique Key in SQL | Differences and How to Use Them | SQL Tutorial

Description:

Welcome to another video in our MS SQL Server Tutorial Series! In this tutorial, we will be exploring the differences between the Primary Key and the Unique Key in SQL. Both of these keys are essential for maintaining data integrity and ensuring that each row in your database is uniquely identifiable. However, there are important differences between them in terms of their behavior, constraints, and usage.

🔑 What You Will Learn in This Video:
What is a Primary Key?
The Primary Key is used to uniquely identify each record in a table. We’ll explain how to define a Primary Key for your tables, and why it's essential for relational database design. We’ll also discuss the NOT NULL constraint that comes with a Primary Key.

What is a Unique Key?
The Unique Key is similar to the Primary Key, but with a few key differences. A Unique Key ensures that all values in a column are distinct, but it allows for NULL values (unlike the Primary Key). We'll dive into the nuances of the Unique Key and demonstrate how it can be used when a Primary Key is not appropriate.

Key Differences Between Primary Key and Unique Key:
Understanding when to use a Primary Key vs a Unique Key is crucial for good database design. We will break down the key differences, including:

Primary Key allows only one per table; Unique Key allows multiple per table.

Primary Key does not allow NULL values; Unique Key allows NULL values.

Primary Key creates a clustered index by default; Unique Key creates a non-clustered index.

How to Use Primary Keys and Unique Keys in SQL:
We will show you how to create both Primary Key and Unique Key constraints using SQL scripts and SQL Server Management Studio (SSMS). This will include creating tables with Primary Key and Unique Key constraints and modifying existing tables.

Best Practices for Using Primary and Unique Keys:
Learn the best practices for using Primary Key and Unique Key in your database design to ensure data consistency, prevent duplicates, and optimize performance.

By the end of this video, you will have a solid understanding of Primary Key and Unique Key in SQL and how to apply them in your database projects to maintain data integrity and optimize table structures.

📚 Why Primary and Unique Keys Matter:
Using Primary Key and Unique Key constraints ensures the integrity of your data. A Primary Key guarantees that each record is unique and can be identified by its key. A Unique Key ensures uniqueness of data in a column but allows for the flexibility of having NULL values. Understanding how to use these constraints correctly will help you avoid data duplication and design more efficient databases.

📈 Topics Covered in This Tutorial:
What is a Primary Key?

Definition and characteristics

Why use a Primary Key in a table

NOT NULL constraint with Primary Keys

What is a Unique Key?

Definition and characteristics

Key differences from Primary Key

Allowing NULLs with Unique Keys

Key Differences Between Primary Key and Unique Key:

NULL handling

Uniqueness enforcement

Indexing behavior

How to Create Primary Keys and Unique Keys:

Creating Primary Keys in SQL

Creating Unique Keys in SQL

Best Practices:

Choosing when to use Primary or Unique Keys

Optimizing database performance using keys

Avoiding common mistakes with Primary and Unique Keys

👉 Watch the full MS SQL Tutorial Playlist here: [Insert Playlist Link]

💻 Who Should Watch This Video?
SQL Beginners: If you're new to SQL and database design, understanding Primary Keys and Unique Keys is crucial for your learning.

Database Administrators (DBAs): As a DBA, managing data integrity and optimizing table structures is a key responsibility, and this video will help you master these constraints.

Software Developers: If you're building applications that interact with SQL databases, understanding these keys will help you design better data models.

Anyone Preparing for SQL Certifications: If you're preparing for an SQL certification exam, you’ll need to know when and how to use Primary Key and Unique Key in your database designs.

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