Understanding Normalization In Database With Example

Normalization has long been a topic in the database administration community. It is important to know basic database normalization before you begin learning database design to avoid database design and application issues later on.

Database normalization is a process that ensures that database tables contain no redundant data and no data with multi-keys i.e. it includes only single occurrence of data for each attribute/column. Normalized database are using to ensure data integrity and to avoid corruption.

Database Normalization in SQL with Examples – SQLServerCentral

Understanding Normalization In Database With Example

Confused about the different types of normalization in databases? This section will help you understand what each type of normalization is, and how to use them.

The three most common forms of normalization are:

1st Normal Form (1NF) – This form ensures that every column in your table contains only one value. It does not ensure that the values are correct or consistent with each other. For example, an email address is made up of two parts, a username and an email domain. The email domain can be split into two columns in this form – one for the user name and one for the email domain name.

2nd Normal Form (2NF) – This form ensures that all non-key attributes of a relation must depend on the whole key. In other words, you cannot have any partial dependencies on a field or row. For example, if value A is dependent on both columns B and C then it violates 2NF because B and C are not part of A’s key value.

3rd Normal Form (3NF) – This form ensures that all non-key attributes must depend on all parts of its primary key value. For example, if value A is dependent on both columns B and C then it violates 3NF because

Normalization is the process of organizing data in a database so that it can be stored and retrieved in a way that will provide the best performance and data integrity.

Normalization is a process that reduces redundancy in a database. Redundancy occurs when two or more attributes (data elements) in a table are functionally dependent on one another. This leads to inconsistency, because changing one attribute requires changing others as well. This can make it difficult to update the data, especially if multiple tables are involved.

There are three levels of normalization:

First normal form (1NF) – The goal of 1NF is to remove any fields that contain repeating groups of data into separate tables. For example, if you had a field called “Name” that contained both first and last names, then you would consider moving this into its own table where each row would have only one value for “Name”. In this case, you would also have to ensure that foreign keys were defined between these tables for the purpose of linking them together later on if needed. You would also need to ensure that no duplicates existed within your database by using unique identifiers such as primary keys or foreign keys which can easily be identified from one another by referencing a common source such as an

Normalization is the process of organizing data in a database so that all redundant data is removed, and only one copy of each piece of data exists.

Normalization is a process that improves the quality of your data and makes it easier to work with.

Normalized tables are organized in such a way that all fields are dependent upon the primary key, which ideally contains no repeating groups (or duplicates) and no nulls.

There are 3 types of normalization:

1NF (First Normal Form), 2NF (Second Normal Form), 3NF (Third Normal Form).

1NF – First Normal Form

First normal form is the most basic level of database normalization. It ensures that each column in a table can only contain one value, or atomic value. In other words, it means that each column contains one and only one attribute. If a column has multiple values then it violates 1NF.

For example, consider the following table:

Table 1: A table violating first normal form

ID Name Age Height Weight City Country 1 John 24 180 65 New York USA 2 Mary 27 170 55 London UK 3 James 33 170 50 Paris France 4 Mark 40 170 40 Rome Italy The above table does not follow 1NF because there are two columns (Name and City) that contain multiple values; therefore this table violates 1NF. To make this table compliant with 1NF we need to remove either City or Name from our table; we can achieve this by using a UNION operator as follows:

Normalization in DBMS: 1NF, 2NF, 3NF and BCNF with Examples


A table is in 1NF if it has no redundant columns and no multi-valued dependent

Normalized Database Architecture. ers.


A table is in 2NF if it is in 1NF and ers that reference a single key of another table, which is called a non-prime ers (aka non-dependent) are removed. A primary key is not required for 2NF.


A table is in 3NF if it is in 2NF and every non-prime ers are removed as well. A primary key is not required for 3NF.

Normalization is a process to organize data in a database. In the process of normalization, all the tables are divided into multiple tables and each table contains a single fact or piece of information. This is done to avoid duplication of data and make data more organized.

Normalization is mainly used to solve these problems:

Duplicate data

Improper relationships between tables

Insertion, update and deletion anomalies

Referential integrity (RI) violation.

The first step in the normalization process is to select a field that will serve as the primary key. A primary key is a field or combination of fields that uniquely identifies each record in a table.

In this example, we’ll use the StudentName field for our primary key.

The next step is to remove any duplicate values for the primary key from your table and place them into their own table. This is known as 1st normal form (1NF). In our example, we have two students with the name “John Smith” so we’ll create a new table called StudentsWithDuplicateNames and move all records with duplicate names into this table:

CREATE TABLE StudentsWithDuplicateNames ( StudentID INTEGER NOT NULL, StudentName CHAR(20) NOT NULL );

INSERT INTO StudentsWithDuplicateNames (StudentID, StudentName) VALUES (1, ‘John Smith’), (2, ‘John Smith’);

Next, you need to identify any columns in your table that contain repeating groups of data and place them into their own tables. In our example, there are three students named “Jane Doe” so we’ll create a new table called StudentsWithRepeatingGroupings and move all records with repeating groupings.

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