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.

• 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 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.

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:

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:

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.