SQL and databases: how to design schema and table normalization?

Designing a database schema and proper table normalization are the foundation of reliable and scalable software. The development process should begin with creating a minimal reproducible example, fixing the version of the DBMS used, and clearly describing the migration steps, as this lays the groundwork for easy debugging in the future.

At the first stage of design, it is necessary to identify all domain entities and determine the relationships between them, whether one-to-one, one-to-many, or many-to-many. Then the data normalization process is applied, which sequentially passes through several normal forms from the first to the third and higher. Normalization helps to completely get rid of information redundancy, prevent anomalies in updating, deleting, and inserting records, and guarantee data integrity in a relational structure.

However, in real development practice, blindly following normalization to the final level can lead to the creation of a huge number of related tables and heavy JOIN operations. Therefore, after completing the normalization stages, developers often apply denormalization for performance-critical parts of the system. A wise balance between a normalized structure and reasonable redundancy allows for building an efficient and maintainable database.