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Let’s look at the first normal form in detail from the previous lecture where we saw a brief overview of the normal forms.

First Normal Form (1NF) is the first level of normalization in database design. It ensures that the data in a table is organized in a way that avoids redundancy and anomalies. The two rules of 1NF are:

• Atomic Values: Only atomic or indivisible values should be present in each column. For instance, the 1NF is violated when a column that stores a list of phone numbers separated by commas has multiple values.
• No Repeating Groups: Only one value should be present in each column. No repeating data sets or multiple values in the same column are acceptable. For example, a column that stores multiple addresses for a single customer violates 1NF because it contains repeating groups of data.

Example: Atomic Value Violation

ID	Name	Age	Contact
1	Ramesh	32	1234567890,21314152
2	Mukesh	40	8978654372
3	Sumit	45	9450012002
4	Kaushik	25	8912342503

The above table violates the 1NF rule as the contact value for first row isn’t atomic. To solve such an issue we will create another table, i.e

ID	Contact
1	1234567890
1	21314152
2	8978654372
3	9450012002
4	8912342503

Example: Repeating Groups

ID	Name	Age	City1	City2	Country
1	Ramesh	32	Hyderabad	Delhi	India
2	Mukesh	40	New York		USA
3	Sumit	45	Muscat		Oman
4	Kaushik	25	Kolkata		India

Because the City column is repeated twice, this table is not in the first normal form, as you can see in the current table. Whether the person stays in two cities or not, this table always allots disc space for two cities.

To eliminate the repeating columns and bring the table to the first normal form, separate the table into two tables. Create one of the tables with the repeating columns as shown below:

ID	Name	Age
1	Ramesh	32
2	Mukesh	40
3	Sumit	45
4	Kaushik	25

ID	City	Country
1	Hyderabad	India
1	Delhi	India
2	New York	USA
3	Muscat	Oman
4	Kolkata	India

Note: also read about Normalization of Database

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