Database Normalization

Normalization is the process of organizing tables in a database according to specific rules to eliminate redundant data data, prevent data loss, and simplify database management. In database design, normalization is applied to create well-structured tables, remove data dependencies, and clarify relationships.

Advantages of Normalization

• Ensures Data Integrity: Since the same data is not stored in multiple places, updates become easier.
• Uses Storage Space Efficiently: By eliminating unnecessary repetitions, less data is stored.
• Improves Performance: Reduces unnecessary query loads in the database, increasing speed.
• Provides Flexibility and Application Independence: Managing and modifying data becomes simpler.

Normalization Rules and Normal Forms

Normalization is based on specific rules applied in levels known as "normal forms." Generally, three primary normal forms are used: 1NF, 2NF, and 3NF. In more complex systems, higher-level forms such as Boyce-Codd Normal Form (BCNF), 4NF, and 5NF like are also applied.

First Normal Form (1NF)

Requirements:

• All columns must be atomic (indivisible).
• Each column must contain data of the same type.
• A unique primary key must exist.

🔹 Example: The following student table does not comply with 1NF because the "Courses" column contains multiple values:

Transformed 1NF Table:

Second Normal Form (2NF)

Requirements:

• The table must satisfy 1NF.
• Partial dependencies must be eliminated; that is, columns dependent on only part of the primary key must be moved to a separate table.

🔹 Example:

In this table, the "Department_name" column depends on "Department_code." Therefore, "Department_name" must be moved to a separate table:

Student Table:

Department Table:

Grades Table:

Third Normal Form (3NF)

Requirements:

• The table must satisfy 2NF.
• Transitive dependencies must be eliminated; that is, non-key columns must not depend on other non-key columns.

🔹 Example: In the table, the "Department_code" information depends on "Department_name." If "Department_name" depends on another column, this creates a transitive dependency situation road. To prevent this, department information should be stored in a separate table.

Final Hali:

Database normalization is a critical method used to ensure data integrity, use storage space efficiently storage and improve performance. 1NF, 2NF, and 3NF are the most commonly used normalization steps common. Boyce-Codd Normal Form (BCNF), 4NF, and 5NF are applied for more complex structures.