normaalimuotoisia

Normaalimuotoisia, often translated as "normal forms" in English, refers to a set of conditions or properties that a data structure, such as a database table, can satisfy. The primary goal of achieving normal forms is to reduce data redundancy and improve data integrity. This is achieved by organizing data in a way that ensures attributes are stored in a logical and efficient manner.

The concept of normalization was introduced by Edgar F. Codd, the inventor of the relational model. There are several levels of normal forms, each building upon the previous one. The most commonly discussed are First Normal Form (1NF), Second Normal Form (2NF), and Third Normal Form (3NF).

First Normal Form (1NF) requires that a table have a primary key and that each column contains atomic (indivisible) values, with no repeating groups of columns. Second Normal Form (2NF) builds on 1NF by requiring that all non-key attributes be fully functionally dependent on the primary key. This means that no non-key attribute should be dependent on only a part of a composite primary key. Third Normal Form (3NF) further refines this by stating that there should be no transitive dependencies. In other words, non-key attributes should not be dependent on other non-key attributes.

Higher normal forms, such as Boyce-Codd Normal Form (BCNF) and Fourth Normal Form (4NF), exist to address more complex dependency issues. While higher normal forms can further reduce redundancy, they can also sometimes lead to more complex queries and a greater number of tables, necessitating trade-offs between data integrity and query performance. The choice of which normal form to achieve depends on the specific requirements and context of the database design.