First normal form

First Normal Form (1NF)

Definition

A table is in First Normal Form (1NF) if each table cell contains a single value, eliminating repeating groups or arrays.

Rules

• Atomic Values: Each table cell must contain atomic values, meaning a single value that cannot be broken down further.
• No Repeating Groups: There should be no repeating groups or arrays in a table.
• Unique Column Names: Each column in a table must have a unique name.

Benefits

• Improved Data Integrity: 1NF helps ensure data integrity by eliminating repeating groups and ensuring atomic values.
• Simplified Querying: 1NF makes querying and manipulating data easier and more efficient.
• Reduced Data Redundancy: 1NF helps reduce data redundancy by eliminating repeating groups.

Example

Consider a table that stores customer information with repeating groups:

Customer ID	Name	Phone Numbers
1	John Doe	123-456-7890, 987-654-3210

To convert this table to 1NF, we would create a separate table for phone numbers:

Customer ID	Name
1	John Doe

Customer ID	Phone Number
1	123-456-7890
1	987-654-3210