Normalization in SQL databases is a process used to organize data in a way that reduces redundancy and improves data integrity. The primary goal of normalization is to divide large tables into smaller, related tables and define relationships between them. This way, each piece of information is stored only once, avoiding the complications that arise when the same data is held in multiple places. Normalization typically involves applying a set of guidelines known as normal forms, which help structure the database logically.
For example, consider a sales database that logs customers, orders, and products. If all information is stored in one table, it might include customer details, product details, and order information all mixed together. This arrangement can lead to issues, such as needing to update customer information in several places or data inconsistency. By normalizing the database, you might separate this information into three tables: one for customers, one for orders, and one for products. Each table relates to the others through foreign keys, allowing you to access relevant information without duplicating it.
Normalization is usually carried out in several steps, known as "normal forms." The first normal form (1NF) requires that each column contains atomic values (indivisible values), while the second normal form (2NF) addresses the need for all non-key attributes to be fully dependent on the primary key. The third normal form (3NF) further eliminates transitive dependencies, ensuring that non-key attributes do not depend on other non-key attributes. By following these steps, developers create a more efficient and maintainable database structure, leading to easier data management and fewer chances for errors or inconsistencies.