What is Normalization in SQL and It's Type - Quick Guide

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As a data wizard, we deal with loads of information spread across many tables in various databases. Obtaining information can be challenging if things need to be organized appropriately. Here comes normalization to fix this. It aids in sorting out the mess, removing unnecessary repetition, and putting everything in order using unique forms. This guide is here to understand the idea of Normalization in SQL.

Normalization in SQL Meaning

Sometimes, you have a bunch of information, like names, numbers, and details about something important, all mixed up. Normalization is the process of tidying up that information to make it organized and easy to use. It's about creating tables and smartly connecting them to keep the information safe. Additionally, it makes it easy to find what you need. By doing this, we get rid of unnecessary repetition and make sure everything makes sense.

Redundant data contain extra copies of the same thing scattered around. As a result, it takes up space and causes problems when you need to update it. That's why it's better to keep things in one spot, like a 'Customers,' so changes are easy to manage. Now, what's an 'inconsistent dependency'? Well, it's like looking for information in the wrong place. In a database, we want to keep things logical. For example, details about employees, like salaries, should be in the 'Employees' section, not mixed up with customer info.

How Does Database Normalization in SQL Impact?

So, when you tidy up your data using normalization, you might end up with more little tables and connections between them. However, some users might worry that this makes writing SQL query normalization problematic. As a result, there are more tables to think about, maybe slower with all those connections.

In spite of that, it's not as challenging as it seems. Here are some merits of dealing with normalization in Structured Query Language:
 

• Less Data to Deal With: You have a bunch of small tables instead of one big messy table.
• Better Performance Tricks: There are some tricks to make your queries faster when you have lots of little tables.

• Easy Changes: When you want to add, update, or delete data, it's easy because you only need to do it in one place.

Now, we will learn about some types of database normalization SQL.

Types of Normalization in SQL

Let's dive into the various SQL normalization rules - The first one is the First Normal Form (1NF). Before proceeding further, we will look over the sorts of names in a list.
 

1. First Normal Form (1NF)
2. Second Normal Form (2NF)
3. Third Normal Form (3NF)
4. Boyce-Codd Normal Form (BCNF)
5. Fourth Normal Form (4NF)
6. Fifth Normal Form (5NF)

Now, we will elaborate on each section in detail.

First Normal Form (1NF)

A table is in first Normal form (1NF) if it has no repeating or array data types. Here, atomicity states a single cell can’t carry numerous values. In short, it holds only a single-valued attribute.

The 1NF doesn’t permit the composite attribute, multi-valued attribute, and their combinations.

Let's talk with an example. Picture a table about students with their roll number, name, course, and age. However, the course part has two things. We want each square to be neat, with only one thing inside.

When we fix it with 1NF, every square has its unique thing, and no more mixing. Before we move on to the following normalization in SQL, let's discuss Candidate Key and Super Key.
 

• Candidate Key or Primary Key

Alright, let's talk about 'Primary Key.' It is the secret code that helps us identify each record uniquely in our database.

Now, Primary Key has some benefits:
 

• No Empty Spaces: A Primary Key can't be empty; it always needs to have something inside it.
• One of a Kind: Every Primary Key has to be unique. In other words, there is no sharing of secret codes here.
• Steady and Strong: We don't want to keep changing our secret code. Once we pick it, it should stay the same.
• Get It from the Start: When inserting a new record, the primary key must have a value assigned to it.
   

• Super Key

A Super Key is a set of one or more keys that can identify a record uniquely in a table. The Primary Key is a subset of the Super Key.

Now, we will elaborate on another kind of normalization in SQL.

Second Normal Form (2NF)

Let's continue with the Second Normal Form (2NF). First off, to be in 2NF. Now, for 2NF, we want to avoid called 'partial dependency.' It should come from their unique skills, not just a part of them.

Now, we will check this out with an example. Suppose a table about locations where the primary key is a combo of cust_id and stored. We've got a subsidiary called store_location, but it only depends on the kept, not the entire primary key.

To fix this, we split the table into two parts – one with cust_id and storeid and another with storeid and store_location. Now, store_location depends on the real primary team, not just a part.

So, by doing this, we've leveled up to 2NF. Moreover, ensuring everything is super organized.

Third Normal Form (3NF)

Alright, let's talk about the Third Normal Form (3NF). 3NF amis to avoid 'transitive dependency.' It shouldn't rely on another power indirectly. Moreover, it has its unique abilities without borrowing from someone else.

Let's check out an example. Visualize a table about students with IDs, names, subject IDs, subject names, and addresses. However, subject names depend on subject IDs and rely on student IDs. That's a transitive dependency, and 3NF doesn't like that.

To fix it, we split the table into two teams – one with student info and another with subject info. Now, each team has its primary key, and everything else depends only on that key.

So, by doing this, we've upgraded to 3NF. The following section will describe the other sorts of normalization in SQL.

Boyce-Codd Normal Form (BCNF)

Let's talk about the Boyce Codd Normal Form (BCNF). Moreover, it is version 3.5 NF. This superhero was created by Raymond F. Boyce and Edgar F. Codd, to tackle some tricky anomalies that 3NF couldn't handle. The third Normal Form (3NF) has some rules. First, the table needs to be in 3NF, and every attribute on the right side (RHS) of the functional dependency should depend on the super key of that table.

Let's look at an example. Picture a table about subjects, where students can enroll in multiple subjects, professors can teach a topic, and each subject gets a professor. However, it seems like there's a dependency – the subject depends on the professor's name.

To fix this and be the functional dependency we need to be, we split the table into two squads – one with student info and another with a Profit. Now, the subject depends only on the functional dependency ID card, and we're BCNF-ready.

Here, we’ve discussed about the Boyce Codd Normal Form. Now, we will elaborate on the other two kinds of normalization in SQL.

Fourth Normal Form (4NF)

This one is like saying if no table has too much info about an entity, and everything is nicely split and independent, it's in 4NF. Moreover, it has their card with just the correct details.

Fifth Normal Form (5NF)

5NF is similar to 4NF but cannot be further broken down without losing information. It cannot be split without missing crucial details.

Concluding Words

Normalization in SQL is a critical aspect of database design. As a result, it ensures data integrity, reduces redundancy, and enhances performance. Moreover, database designers can create reliable and scalable database schemas that meet their application's requirements by understanding the principles of normalization and applying them effectively. However, it is essential to strike a balance between normalization and performance optimization to achieve an optimal database design.

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