What is Normalization in SQL? 1NF, 2NF, 3NF and BCNF in DBMS
Normalization in SQL is a process used to organize a relational database into tables and columns in such a way that it minimizes redundancy and dependency. This process involves dividing large tables into smaller ones and defining relationships between them. The main goal of normalization is to improve data integrity, reduce redundancy, and ensure that the database structure supports efficient querying and updating.
Normalization is typically carried out through a series of normal forms, each addressing specific kinds of problems related to data redundancy and dependency. The commonly discussed normal forms are:
1. **First Normal Form (1NF):**
- A table is said to be in 1NF if it contains only atomic values and there are no repeating groups or arrays within the table.
- In simpler terms, each column in a 1NF table must contain only a single value, and each row must be uniquely identifiable.
2. **Second Normal Form (2NF):**
- A table is in 2NF if it is in 1NF and every non-key attribute is fully functionally dependent on the primary key.
- This means that all attributes must depend only on the entire primary key, not on any part of it. If an attribute depends on only a part of the primary key, it violates 2NF and should be moved to a separate table.
3. **Third Normal Form (3NF):**
-A table is in 3NF if it is in 2NF and there is no transitive dependency.
- Transitive dependency occurs when a non-key attribute is functionally dependent on another non-key attribute, rather than directly on the primary key.
- To achieve 3NF, you must remove such dependencies by moving the dependent attributes to a separate table.
4. **Boyce-Codd Normal Form (BCNF):**
- BCNF is an advanced form of normalization that eliminates all non-trivial functional dependencies.
- A table is in BCNF if, for every non-trivial functional dependency X → Y, X is a superkey. In other words, every determinant (X) must be a candidate key.
- BCNF ensures that every dependency in a table is a dependency on a candidate key, eliminating redundancy even further than 3NF.
In summary, normalization in SQL involves structuring tables and their relationships in a way that minimizes redundancy and dependency, leading to better data integrity and query performance. It is an essential concept in database design to ensure that databases are efficient, maintainable, and scalable.
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