Normalization is a systematic process of organizing data in a database to minimize redundancy and dependency by dividing larger tables into smaller ones and linking them using relationships.
- It ensures that the database structure is efficient and maintains data integrity.
Importance of Normalization:
1.) Eliminates Data Redundancy:
- Normalization reduces unnecessary duplication of data across tables.
2.) Ensures Data Integrity:
- By organizing data into logical tables, normalization ensures that updates, deletions, and insertions are handled consistently. This minimizes the chance of data anomalies like update, deletion, or insertion anomalies.
3.) Simplifies Maintenance:
- A normalized database is easier to maintain because changes in one place automatically propagate to related tables without requiring manual adjustments.
4.) Supports Data Scalability:
- As the database grows, normalization helps manage the data structure efficiently without becoming overly complex or inconsistent.
5.) Reduces Storage Requirements:
- While initial normalization may increase the number of tables, it reduces the overall storage by eliminating redundant data.
6.) Enhances Data Consistency:
- By ensuring each piece of data is stored in one place, normalization prevents conflicting versions of the same data.
Types of Normalization:
- Unnormalized Form (UNF)
- First Normal Form (1NF)
- Second Normal Form (2NF)
- Third Normal Form (3NF)
- Boyce-Codd Normal Form (BCNF)
- Fourth Normal Form (4NF)
- Fifth Normal Form (5NF)
1.) Unnormalized Form (UNF)
- A table is said to be in Unnormalized Form (UNF) if it contains a multivalued attribute, composite attributes, or both. In this form, data redundancy exists, and the structure is not optimized for efficient querying.

2.) First Normal Form (1NF)
- A table is said to be in First Normal Form (UNF) if it does not contain multivalued attribute or composite attributes, or both.

3.) Second Normal Form (2NF)
- A table is in Second Normal Form (2NF) if it is in 1NF, and all non-prime attributes are fully functionally dependent on the primary key. Partial dependencies are eliminated.
Rules:
- The table must be in 1NF.
- Every non-prime attribute should be fully dependent on the entire primary key.
4.) Third Normal Form (3NF)
- A table is in Third Normal Form (3NF) if it is in 2NF, and all non-prime attributes are directly dependent only on the primary key.
5.) Boyce-Codd Normal Form (BCNF)
- A table is in Boyce-Codd Normal Form (BCNF) if it is in 3NF, and for every functional dependency (A → B), A must be a superkey.
Rules:
- The table must be in 3NF.
- Each determinant (left-hand side of the functional dependency) must be a superkey.
6.) Fourth Normal Form (4NF)
- A table is in Fourth Normal Form (4NF) if it is in BCNF, and does not contain multivalued attribute.
7.) Fifth Normal Form (5NF)
- A table is in Fifth Normal Form (5NF) if it is in 4NF, and all join dependencies are preserved without introducing redundancy.