Database Normalization

Introduction

Database normalization is the process of organizing data in a database to minimize data redundancy and dependency.

Benefits

• Eliminates Data Redundancy: Normalization helps eliminate data redundancy, reducing storage needs and improving data consistency.
• Improves Data Integrity: Normalization ensures that data is consistent and follows rules, reducing errors and inconsistencies.
• Improves Scalability: Normalization makes it easier to modify and extend the database structure as needed.

Normal Forms

• First Normal Form (1NF): Each table cell contains a single value, eliminating repeating groups.
• Second Normal Form (2NF): Each non-key attribute depends on the entire primary key, eliminating partial dependencies.
• Third Normal Form (3NF): If a table is in 2NF, and a non-key attribute depends on another non-key attribute, then it should be moved to a separate table.
• Boyce-Codd Normal Form (BCNF): A table is in BCNF if it is in 3NF, and there are no transitive dependencies.
• Higher Normal Forms: There are additional normal forms, such as 4NF and 5NF, that deal with multi-level dependencies and join dependencies.

Normalization Process

• Identify Entities: Identify the entities and attributes in the database.
• Identify Relationships: Identify the relationships between entities.
• Apply Normalization Rules: Apply the normalization rules to eliminate data redundancy and dependency.

Denormalization

• When to Normalize

  • New Database Design: Normalize during the initial database design phase.
  • Database Refactoring: Normalize existing databases to improve performance and data integrity.

  Common Normalization Mistakes

  • Over-Normalization: Excessive normalization can lead to complex queries and decreased performance.
  • Under-Normalization: Insufficient normalization can lead to data redundancy and inconsistencies.