What is Normalization in SQL? | Database Normalization Forms - 1NF, 2NF, 3NF, BCNF | Edureka

Summary

This video script by Predict from Ed Eureka dives into the concept of database normalization, a systematic approach to organizing data and eliminating redundancy. It covers the basics of normalization, including First, Second, and Third Normal Forms, as well as the Boyce-Codd Normal Form. The script explains how normalization addresses data anomalies like insertion, update, and deletion issues, ensuring data integrity and logical sense. With simple examples, it guides viewers through the process of achieving each normal form, emphasizing the importance of atomicity, avoiding partial dependencies, and ensuring non-prime attributes' dependencies are direct and logical.

Takeaways

• 😀 Database normalization is a systematic approach to organizing data and eliminating redundancy by decomposing tables.
• 🔑 The primary purpose of normalization is to remove repeated data and ensure data dependencies make logical sense.
• 📊 Normalization helps to address data anomalies such as insertion, update, and deletion anomalies, which can cause data inconsistency and inefficiency.
• 📝 There are different levels of normal forms, including First Normal Form (1NF), Second Normal Form (2NF), Third Normal Form (3NF), and Boyce-Codd Normal Form (BCNF).
• 🧩 In 1NF, the table should have atomic values, meaning no cell should hold multiple values, and each set of related data is identified with a primary key.
• 🔄 2NF requires a table to be in 1NF and to eliminate partial dependencies where non-prime attributes depend on only a part of the primary key.
• 🔄 3NF builds on 2NF by ensuring that non-prime attributes are not transitively dependent on other non-prime attributes, but only on the primary key.
• 🔍 BCNF is an extension of 3NF, addressing cases where functional dependencies violate the rule that every determinant must be a super key.
• 🛠️ Normalization is crucial for maintaining data integrity, reducing the need for restructuring, and making the data model more informative.
• 📈 The process of normalization involves breaking down tables to eliminate data redundancy and anomalies, thus improving the overall database design.
• 💻 Understanding and applying normalization principles is essential for database administrators and designers to manage large datasets effectively.

Q & A

What is normalization in the context of databases?

Normalization is a systematic approach to organizing data in a database by decomposing tables to eliminate data redundancy. It involves a multi-step process that puts data into a tabular form, removing duplicated data from relational tables.

Why is normalization necessary for database management?

Normalization is necessary to eliminate repeated data and ensure data dependencies make logical sense. It helps to prevent data anomalies, reduce the need for restructuring over time, and make the data model more informative.

What are the different types of normalization forms discussed in the script?

The script discusses First Normal Form (1NF), Second Normal Form (2NF), Third Normal Form (3NF), and Boyce-Codd Normal Form (BCNF).

What is the main goal of achieving the First Normal Form (1NF)?

The main goal of achieving 1NF is to ensure atomicity, meaning that values in the table should not be further divided and a single cell cannot hold multiple values.

Can you explain the concept of 'partial dependency' in the context of Second Normal Form (2NF)?

In 2NF, partial dependency refers to a situation where a non-prime attribute (an attribute not part of any candidate key) is dependent on a proper subset of a candidate key, rather than the entire candidate key.

What is the primary condition for a table to be in Third Normal Form (3NF)?

For a table to be in 3NF, it must first be in 2NF, and second, it must not have any transitive dependency where a non-prime attribute is dependent on another non-prime attribute.

What are the main problems that normalization aims to solve, as mentioned in the script?

Normalization aims to solve data anomalies such as insertion, update, and deletion anomalies, which can lead to data inconsistency and inefficiency in database management.

How does the Boyce-Codd Normal Form (BCNF) differ from Third Normal Form (3NF)?

BCNF is a higher version of 3NF and addresses certain types of anomalies not dealt with by 3NF. In BCNF, every functional dependency implies that the attribute(s) on the left side of the dependency must be a super key of the table.

What is a 'super key' in the context of Boyce-Codd Normal Form (BCNF)?

A super key in BCNF is a combination of one or more attributes that uniquely identifies rows in a table.

Can you provide an example of how to apply the concepts of normalization to a database table?

An example from the script is the employee table with columns for employee ID, name, phone number, and salary. If the phone number column has multiple values, it violates 1NF. To achieve 1NF, the phone number column could be split into separate rows or a new table with a foreign key reference to the employee ID.

What are the benefits of normalizing a database according to the script?

The benefits of normalizing a database include eliminating data redundancy, reducing the risk of data anomalies, improving data integrity, and making the database more efficient and easier to maintain.

Outlines

00:00

😀 Introduction to Database Normalization

The video script introduces the concept of database normalization, a systematic approach to organizing data to eliminate redundancy and improve data integrity. The session is led by Predict from Ed Eureka, who outlines the agenda, which includes understanding normalization, exploring various normal forms such as first, second, third normal forms, and the Boyce-Codd normal form. The importance of normalization is emphasized to avoid data anomalies like insertion, update, and deletion anomalies, which can lead to data inconsistencies and inefficiencies. The script also encourages viewers to subscribe to the channel for updates.

05:03

📚 Achieving First Normal Form (1NF)

This paragraph delves into the specifics of the first normal form (1NF), which addresses the issue of atomicity in database tables. It explains that a table should not contain composite or multivalued attributes, and that each cell should hold a single value. The process of achieving 1NF involves removing repeating groups and creating separate tables for related data, each identified by a primary key. An example is provided where an employee table with a phone number column containing multiple values is split into a table that adheres to 1NF, ensuring no cell contains multiple values.

10:05

🔑 Understanding Second Normal Form (2NF)

The second paragraph explains the second normal form (2NF), which builds upon 1NF by eliminating partial dependencies. It defines partial dependency as a situation where a non-prime attribute is dependent on only a part of a composite primary key. To satisfy 2NF, the table must be in 1NF and have no partial dependencies. An example is given where a table with a composite primary key of employee ID and department ID is split into two tables to remove the partial dependency of the office location on department ID alone. The result is two tables, each with a primary key and non-key attributes fully functionally dependent on that key.

🔄 Transitioning to Third Normal Form (3NF)

The third normal form (3NF) is discussed in this paragraph, focusing on reducing data duplication and ensuring referential integrity by eliminating transitive dependencies. A table must be in 2NF and have no non-prime attribute transitively dependent on another non-prime attribute to be in 3NF. The explanation simplifies the concept by using an example where a table with a transitive dependency between student ID, subject ID, and subject is split into two tables to achieve 3NF. The result is that all non-key attributes in the first table are dependent only on the primary key, and in the second table, the subject is dependent only on subject ID.

🎓 Boyce-Codd Normal Form (3.5NF)

The final paragraph introduces the Boyce-Codd normal form (3.5NF), which is an extension of 3NF designed to address certain anomalies not covered by 3NF. In 3.5NF, every non-trivial functional dependency implies that the left side of the dependency is a super key. The paragraph uses an example of a table with student ID, subject, and professor, where the professor is dependent on the subject, which is a prime attribute. To satisfy 3.5NF, the table is divided into two, with the second table having professor ID as a super key, thus removing the non-prime attribute's functional dependency. The session concludes with an invitation for viewers to ask questions and engage with the content.

Keywords

💡Normalization

Normalization is a systematic approach in database management to organize data by decomposing tables and eliminating redundancy. It is central to the video's theme as it is the primary technique discussed for organizing data in a database. The script mentions various types of normalization, such as first, second, third normal forms, and Boyce-Codd normal form, to illustrate the process of refining data structures for efficiency and consistency.

💡Data Redundancy

Data redundancy refers to the duplication of data across a database, which can lead to inefficiencies and data anomalies. In the context of the video, normalization is presented as a solution to reduce data redundancy, ensuring that each piece of information is stored only once, thus simplifying data management and reducing storage requirements.

💡First Normal Form (1NF)

First Normal Form is the initial step in the normalization process, focusing on atomicity, which means that table cells should not contain multiple values. The video script uses the example of an employee table to demonstrate how to achieve 1NF by ensuring that each cell contains a single value and splitting composite attributes into separate tables.

💡Second Normal Form (2NF)

Second Normal Form builds upon the first by addressing partial dependencies, where non-prime attributes are dependent on only a part of a composite primary key. The script explains 2NF by illustrating how to split a table to ensure that non-key attributes are fully functionally dependent on the primary key, thus eliminating partial dependencies.

💡Third Normal Form (3NF)

Third Normal Form further refines the database by eliminating transitive dependencies, where non-prime attributes depend on other non-prime attributes through the primary key. The video script provides an example of a student-subject relationship table and shows how to restructure it to ensure that only prime attributes determine non-prime attributes, achieving 3NF.

💡Boyce-Codd Normal Form (BCNF)

Boyce-Codd Normal Form, also known as 3.5NF, is an extension of third normal form that deals with certain types of anomalies not addressed by 3NF. The script explains BCNF by showing how to restructure a table to ensure that every non-trivial functional dependency is a super key, thus avoiding functional dependencies on non-prime attributes.

💡Data Anomalies

Data anomalies are problems that arise from improper data organization, such as insertion, update, and deletion anomalies. The video script discusses these anomalies to highlight the need for normalization, explaining how they can lead to data inconsistencies and the necessity of restructuring to maintain data integrity.

💡Composite Key

A composite key is a primary key made up of two or more attributes that together uniquely identify a record in a table. The video script uses the concept of a composite key to explain how partial dependencies can occur in second normal form and how to resolve them by splitting the table.

💡Functional Dependency

Functional dependency is a relationship between attributes in a table where the value of one attribute determines the value of another. The video script discusses functional dependencies in the context of normalization, explaining how they should be managed to achieve the various normal forms and avoid data anomalies.

💡Super Key

A super key is any set of attributes that uniquely identifies a record in a table, which may include a combination of one or more attributes. The script introduces the concept of a super key in the context of Boyce-Codd normal form, emphasizing that every functional dependency should be on a super key to satisfy BCNF.

💡Insertion Anomaly

Insertion anomaly occurs when new data cannot be added to a table because of missing related information. The video script provides an example of an insertion anomaly where adding a new employee without a department would require setting the department information as null, illustrating the problem and the need for normalization.

💡Update Anomaly

Update anomaly happens when changes in the data require updating multiple records, risking data inconsistency if some records are missed. The script uses the example of updating Mr. Ratchett's department change to explain how update anomalies can occur and the importance of normalization in preventing them.

💡Deletion Anomaly

Deletion anomaly arises when deleting a record also removes associated information that should be retained. The video script describes a scenario where deleting employee records at the end of a financial year would also delete department information, demonstrating the need for normalization to avoid such data loss.

Highlights

Normalization is a systematic approach to organizing data in a database to eliminate data redundancy.

There are different types of normalization including first, second, third normal form, and Boyce-Codd normal form.

Normalization helps to eliminate repeated data and ensure data dependencies make logical sense.

Data anomalies such as insertion, update, and deletion anomalies can occur if a table is not properly normalized.

First normal form (1NF) tackles the problem of atomicity, ensuring no cell holds multiple values.

Second normal form (2NF) requires tables to be in 1NF and to not contain partial dependencies.

In 2NF, non-prime attributes should be fully dependent on the primary key, not just a part of it.

Third normal form (3NF) further reduces data duplication and ensures referential integrity.

3NF requires tables to be in 2NF and that no non-prime attribute is transitively dependent on another non-prime attribute.

Boyce-Codd normal form (BCNF) is a higher version of 3NF, addressing anomalies not covered by 3NF.

In BCNF, every functional dependency implies that the determinant must be a super key of the table.

Normalization reduces the need for restructuring over time and makes the data model more informative.

Examples are provided to illustrate how to achieve each normal form by decomposing tables.

The video explains how to identify and correct data anomalies through the process of normalization.

Understanding normalization helps in managing large datasets and maintaining data consistency.

The session concludes with an invitation for viewers to ask questions and engage with the content.

The presenter encourages viewers to like, comment, and subscribe for more educational content.

The video aims to provide a clear understanding of normalization and its practical applications in database management.

Transcripts

[Music]

dito in the database is stored in terms

of enormous quantity retrieving certain

data will be a tedious task if the data

is not organized correctly with the help

of normalization we can organize this

data and also reduce the redundant data

hey guys this is predict from Ed Eureka

and I welcome you all to this

interesting session on normalization in

SQL in this session I'll explain

everything that is related to

normalization with simple examples that

are easy to remember firstly let's look

at the agenda for today's session so

we're going to start off with

understanding normalization and moving

further we shall look at various types

of normalization and those are first

normal form second normal form third

normal form and boyce-codd normal form I

hope you guys are clear with the agenda

but before moving further if you haven't

subscribed to a channel then do

subscribe to never miss out an update

with that being said let's get started

the first topic in today's session is

what is normalization database

normalization is a technique of

organizing the data in the database it

is a systematic approach of decomposing

tables to eliminate data redundancy it

is a multi-step process that puts data

into tabular form removing the

duplicated data from its relational

tables on the screen we just saw that

the table is getting decomposed into two

smaller table is it really necessary to

normalize the table that is present on

the database well every table in the

database has to be in the normal form so

normalization is used mainly for two

purpose so the first one is it is used

to eliminate repeated data having

repeated data in the system not only

makes the process flow but will cause

trouble during the later part of

transactions and second one is to ensure

the data dependencies make some logical

sense yes usually the data is stored in

database with certain logic huge data

sets without any purpose are completely

waste it's like having an abundant

resource without any application

the data that we have should make some

logical sense normalization came into

existence because of the problems that

occurred on data now let's look at those

problems and these are known as data

anomalies if a table is not properly

normalized and has data redundancy then

it will not only eat up the extra memory

space but will also make it difficult to

handle and update the data base let's

look at the first anomaly that is

insertion anomaly suppose for a new

position in a company mr. Ratchett is

selected but the department has not been

allotted for him in that case if we want

to update his information to the

database we need to set the department

information as null similarly if we have

to insert data of thousand employees who

are in similar situation then the

department information will be repeated

for all those thousand employees this

scenario is a classical example of

insertion anomalies the next one is

update anomaly what if mr. Ratchett

leaves the company or is in no longer

the head of the marketing department in

that case all the employee records will

have to be updated and if by mistake we

miss any record it will lead to data

inconsistency this is nothing but

updation anomaly and the final one is

deletion anomaly in our employee table

two different pieces of information are

kept together that is employee

information and Department information

hence at the end of financial year

if employee records are deleted we will

also lose the department information

this is nothing but deletion anomaly so

these were some of the problems that

occurred while managing the data to

eliminate all these anomalies

normalization came into existence

there are many normal forms which are

still under development but let's focus

on the very basic and the essential ones

only so we will be talking about first

normal form second normal form third

normal form and finally end this session

with boyce-codd normal form so without

wasting for the time let's proceed your

first normal form

in first normal form we tackle the

problem of atomicity here at alma city

means values in the table should not be

further divided in simple terms a single

cell cannot hold multiple values if a

table contains a composite or

multivalued attributes it violates the

first normal form so the following

functions will be performed in first

normal form the first one is it removes

repeating groups from the table and next

it creates a separate table for each set

of related data and finally it

identifies each set of related data with

the primary key to understand this in a

better way let's look at the given table

in the employee table we have employee

ID employee name phone number and salary

as columns we can clearly see that the

phone number column has two values thus

it violates the first normal form now if

we apply the first normal form to the

above table we get the following result

in this table each and every row is

listing that is no cell has multiple

values the table has achieved a dhama

city first normal form is simple and can

be easily identified in the table we can

clearly see there is no multiple values

in each and every column thus the first

normal form is achieved now let's move

to the second normal form second normal

form was originally defined by EF chord

in 1971 a table is said to be in second

normal form only when it fulfills the

following condition the first condition

is it has to be in first normal form and

the second one is the table also should

not contain partial dependency here

partial dependency means the proper

subset of a candidate key determines a

non-prime attribute so what is a

non-prime attribute let's understand

this in a simple way attributes that

form a candidate key in a table or

called Prime attributes and the rest of

the attributes of the relation are non

prime for a table prime attributes can

be like employee ID and Department ID

and the non prime attributes can be like

office location to understand second

normal form let's consider this table

this table has a composite primary key

that is employee ID and department ID

makes a primary key the non key

attribute is office location in this

case office location only depends on

department ID which is only the power of

primary key

therefore this table does not satisfy

the second normal form so what to do in

such scenario the answer is simple

split the table accordingly to bring

this table to second normal form we need

to break the table into two parts which

will give the following tables the first

table has employee ID and department ID

as columns the second one has department

ID and office location as columns as you

can see we have removed the partial

functional dependency that we initially

had now in the table the column office

location is fully dependent on the

primary key of that table which is

nothing but department ID I hope you

understood second normal form now that

we have learned first normal form and

second normal form let's head to the

next part of this normalization next

topic is third normal form third normal

form is a normal form that is used in

normalizing the table to reduce the

duplication of data and ensure

referential integrity the following

condition has to be met by the table to

be in third normal form and the first

condition is the table has to be in

second normal form and the second

condition is no non-prime attribute is

transitively dependent on any non-prime

attribute which depends on other non

prime attributes

I know it's bit confusing so let me make

it simple for you it's like if C is

dependent on B and in turn B is

dependent on a then transitively C is

dependent on a this should not happen in

third normal form all the non prime

attributes must depend only on the prime

attributes

these are the two necessary condition

that needs to be attained so why was the

normal form design firstly to eliminate

undesirable data anomalies next one is

to reduce the need for restructuring

over time and finally to make the data

model more informaiton since we have

understood the third normal form let's

look at the example table in the above

table student ID determines subject ID

and subject ID determine subject

therefore student ID determines subject

yr subject ID this implies that we have

transitive functional dependency and

this table does not satisfy the third

normal form now in order to achieve the

normal form we need to divide the table

as shown below

firstly let's divide the table and store

student ID student name subject ID and

address in it all the columns are

referring to the primary key which is

student ID let the second table have

subject ID and subject column so subject

is dependent only on subject ID and not

on student ID as you can see from the

above table all the non-key attributes

are now fully functionally dependent

only on the primary key in the first

table column such as student name

subject ID and address are only

dependent on student ID in the second

table subject is only dependent on

subject ID with this being understood

now we can proceed further to next

normal form that is Boyce Codd normal

form this is also known as 3.5 normal

form it is the higher version of third

normal form and was developed by Raymond

F boys and Edgar F Codd to address

certain types of anomalies which were

not dealt with third normal form before

proceeding to Boyce Codd normal form the

table has to satisfy third normal form

in Boyce Codd normal form if every

functional dependency that is a implies

B then a has to be the super key of that

particular table so what is a super key

a super key is a group of single or

multiple keys which identifies rows in a

table let's look at the table to clearly

understand Boyce Codd normal form

in the given table one student can

enroll for multiple subjects there can

be multiple professor teaching one

subject and for each subject a professor

is assigned to the student these are the

necessary condition of the stable in

this table all the normal forms are

satisfied except boyce-codd normal form

Y as you can see that student ID and

subject form the primary key which means

that the subject column is prime

attribute but there is one more

dependency that is professor is

depending on subject and well subject is

a prime attribute professor is a

non-prime attribute which is not allowed

by boyce-codd normal form now in order

to satisfy the boyce-codd normal form we

will be dividing the table into two

parts the table at the top will hold

student ID which already exists and we

will create a new column that is

professor ID and in the second table

which is below we'll have the columns

professor ID professor and subject

columns why do we need to have a new

column that is professor ID by doing

this we are removing the non prime

attributes functional dependency in the

second table professor ID will be the

super key of that table

and remaining column will be

functionally dependent on it by doing

this we are satisfying boyce-codd normal

form so this brings us to the end of

this session I hope you have clearly

understood the normalization and its

different types if you have any queries

or doubts regarding this session please

let me know in the comment section and

I'll get back to you with an answer

thank you guys for watching this video

and have a great day

I hope you have enjoyed listening to

this video please be kind enough to like

it and you can comment any of your

doubts and queries and we will reply

them at the earliest do look out for

more videos in our playlist and

subscribe to any rekha channel to learn

more happy learning