How can database structure be normalized?

Normalization is used to bring the database structure to a normalized form — a process of splitting tables and eliminating data redundancy. The main methods are:

1. First Normal Form (1NF) — all fields contain atomic values, no repeating groups.
2. Second Normal Form (2NF) — the table is in 1NF, and all non-key attributes depend fully on the primary key.
3. Third Normal Form (3NF) — the table is in 2NF, and there are no transitive dependencies between non-key attributes.

Practically, this means creating separate tables for related entities and establishing relationships between them through foreign keys. For example, if one table stores data about orders and customers, normalization involves creating a separate customers table and linking to it from the orders table.

This approach reduces data duplication and increases the integrity of the database.