How can you identify the right normalization form for your database design?

1 First Normal Form (1NF)

The first normal form (1NF) is the simplest and most basic form of normalization. It requires that every table has a primary key, which is a unique identifier for each row, and that every column contains atomic values, which are indivisible and single-valued. For example, a column that stores the name and address of a customer as one value would violate 1NF, because it is not atomic. To achieve 1NF, you would need to split the column into separate columns for each attribute, such as name, street, city, and so on. The benefit of 1NF is that it eliminates repeating groups and ensures that each row represents a single entity.

2 Second Normal Form (2NF)

The second normal form (2NF) builds on 1NF and adds another condition: every non-key column must depend on the whole primary key, not just a part of it. This means that if a table has a composite primary key, which is a combination of two or more columns, then every other column must be related to all the columns in the key, not just some of them. For example, a table that stores the order details of a customer, such as product name, quantity, price, and date, would violate 2NF if the primary key is composed of customer ID and product name, because the quantity, price, and date columns only depend on the product name, not the customer ID. To achieve 2NF, you would need to create a separate table for the order details, with a foreign key that references the customer ID and product name in the original table. The benefit of 2NF is that it eliminates partial dependencies and reduces the risk of data anomalies.

3 Third Normal Form (3NF)

The third normal form (3NF) builds on 2NF and adds another condition: every non-key column must depend only on the primary key, not on any other non-key column. This means that if a table has any transitive dependencies, which are indirect relationships between columns, then it violates 3NF. For example, a table that stores the customer details, such as name, address, phone number, and email, would violate 3NF if the email column depends on the name column, because the email is not directly related to the primary key, which is the customer ID. To achieve 3NF, you would need to create a separate table for the email address, with a foreign key that references the customer ID in the original table. The benefit of 3NF is that it eliminates transitive dependencies and ensures that each table represents a single concept.

4 Higher Normal Forms

There are higher normal forms beyond 3NF, such as Boyce-Codd normal form (BCNF), fourth normal form (4NF), and fifth normal form (5NF), which address more complex and rare cases of data dependencies. However, for most practical purposes, 3NF is sufficient to achieve a good database design that is consistent, efficient, and easy to maintain. Higher normal forms may introduce more complexity and fragmentation to the data model, which could affect the performance and usability of the database.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?