4.1. Normalization About

  • Entities - rows in database

  • Attributes - columns in database

  • Normalization is what gives data meaning

  • NF - Normal Form

  • In order to be in 3rd normal form, you need to be in 1st and 2nd NF

  • Core basics: 1st, 2nd, 3rd

  • Exceptions: 4th, 5th

  • 1st: atomic values, unique identifiers (PK), columns with same type

  • 2nd: all data must depend on the Primary Key

  • 3rd: PK define all Non-Key columns, those can't depend on any other Key

  • 4th: No multi-valued dependencies

4.1.1. Normal forms

  • UNF: Unnormalized form

  • 1NF: First normal form

  • 2NF: Second normal form

  • 3NF: Third normal form

  • EKNF: Elementary key normal form

  • BCNF: Boyce–Codd normal form

  • 4NF: Fourth normal form

  • ETNF: Essential tuple normal form

  • 5NF: Fifth normal form

  • DKNF: Domain-key normal form

  • 6NF: Sixth normal form

4.1.2. Glossary


Database normalization is the process of structuring a database, usually a relational database, in accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity. Normalization entails organizing the columns (attributes) and tables (relations) of a database to ensure that their dependencies are properly enforced by database integrity constraints. It is accomplished by applying some formal rules either by a process of synthesis (creating a new database design) or decomposition (improving an existing database design). A relational database relation is often described as 'normalized' if it meets third normal form. [1] [2]


Normal Form


Rows in database


Columns in database


Database Table

4.1.3. Recap


Figure 4.3. Image credit: [3]

4.1.4. References