2. First Normal Form (1NF)
What is First Normal Form?
- A type of database normalization where a table has no groups/arrays of data
A database is in 1NF if:
- Each column contains only a single value per row (i.e. no lists of values in a column)
- Each column contains only one type of data
- No two rows are identical
- This means there is a unique identifer for each row, usually a primary key
Examples
Example of a table not in 1NF
Customer Orders
| order_id | customer_name | products |
|---|---|---|
| 1 | Alice | Apples, Oranges |
| 2 | Bob | Bananas |
| 3 | Alice | Apples, Bananas |
- Issue: The
productscolumn contains multiple values (lists of products). - How to Convert to 1NF:
- Split the repeating group into individual rows.
- Ensure each column contains only a single value for each record.
Table in 1NF
Customer Orders
| order_id | customer_name | product |
|---|---|---|
| 1 | Alice | Apples |
| 1 | Alice | Oranges |
| 2 | Bob | Bananas |
| 3 | Alice | Apples |
| 3 | Alice | Bananas |
- Fix: The
productscolumn is split, and each product is stored in its own row.
Benefits of 1NF
- Avoids the issues of storing multiple values in a single field.
- Simplifies querying the database (e.g., finding which customers ordered a specific product).
- Ensures that each piece of data is atomic and easily manageable.