Database Normalization Overview

Database Normalization

• Definition:

  • The process of organizing a database to minimize redundancy and dependency by dividing large tables into smaller, related tables.

• Goals:

  • Eliminate redundant data.
  • Ensure data dependencies make sense (i.e., only storing related data in a table).
  • Enhance data integrity and consistency.

• Normalization Forms:

  • First Normal Form (1NF):

    • Ensures each column contains atomic values (no repeating groups or arrays).
    • Each entry in a column must be of the same data type.

  • Second Normal Form (2NF):

    • Builds on 1NF by removing subsets of data that apply to multiple rows and creating separate tables for them.
    • All non-key attributes must depend on the whole primary key (not just part of it).

  • Third Normal Form (3NF):

    • Builds on 2NF and removes transitive dependencies (where a non-key attribute depends on another non-key attribute).
    • Non-key attributes must depend only on the primary key.

  • Boyce-Codd Normal Form (BCNF):

    • A stricter version of 3NF.
    • Every determinant must be a candidate key.

  • Fourth Normal Form (4NF):

    • Addresses multi-valued dependencies.
    • Ensures no table contains two or more independent multi-valued data describing the same entity.

  • Fifth Normal Form (5NF):

    • Deals with cases when information can be split into multiple tables without losing information.
    • Ensures that all facts can be reconstructed from smaller pieces.

• Benefits:

  • Reduces data redundancy.
  • Improves data integrity.
  • Enhances query performance and efficiency.
  • Simplifies data maintenance and updating.

• Considerations:

  • Over-normalization can lead to complex queries and may impact performance.
  • Balance between normalization for data integrity and denormalization for performance.

Database Normalization

• Definition: Organizing a database to minimize redundancy and dependency by dividing large tables into smaller, related tables.
• Goals:
  • Eliminate redundant data.
  • Ensure data dependencies make sense by storing related data in a table.
  • Enhance data integrity and consistency.

Normalization Forms

• First Normal Form (1NF):
  • Columns contain atomic values (no repeating groups or arrays).
  • Each entry in a column has the same data type.
• Second Normal Form (2NF):
  • Builds on 1NF by removing subsets of data that apply to multiple rows, creating separate tables.
  • All non-key attributes depend on the whole primary key (not just part of it).
• Third Normal Form (3NF):
  • Builds on 2NF.
  • Removes transitive dependencies, where a non-key attribute depends on another non-key attribute.
  • Non-key attributes must depend only on the primary key.
• Boyce-Codd Normal Form (BCNF):
  • A stricter version of 3NF.
  • Every determinant must be a candidate key.
• Fourth Normal Form (4NF):
  • Addresses multi-valued dependencies.
  • Ensures no table contains two or more independent multi-valued data describing the same entity.
• Fifth Normal Form (5NF):
  • Deals with cases where information can be split into multiple tables without losing information.
  • Ensures that all facts can be reconstructed from smaller pieces.

Benefits

• Reduces data redundancy.
• Improves data integrity.
• Enhances query performance and efficiency.
• Simplifies data maintenance and updating.

Considerations

• Over-normalization can lead to complex queries and impact performance.
• Balance between normalization for data integrity and denormalization for performance.