Database normalization is a process of organizing data in a database to reduce data redundancy and improve data integrity. It is based on the idea that data should be stored in a single place and that all references to that data should point to the same place.
Normalization is achieved by breaking down a database into smaller tables and defining relationships between the tables. Each table should store a single type of entity, and each row in a table should uniquely identify a single entity.
There are six levels of database normalization, but the most common levels are first normal form (1NF), second normal form (2NF), and third normal form (3NF).
First normal form (1NF)
A database is in 1NF if and only if:
- All attribute values are atomic (i.e., they cannot be further subdivided).
- All attributes are non-repeating.
Second normal form (2NF)
A database is in 2NF if and only if it is in 1NF and all non-key attributes are fully functionally dependent on the primary key.
Third normal form (3NF)
A database is in 3NF if and only if it is in 2NF and all non-key attributes are not transitively dependent on the primary key.
MCQs and Answers
Q1. What is database normalization?
(A) A process of organizing data in a database to reduce data redundancy and improve data integrity. (B) A process of breaking down a database into smaller tables and defining relationships between the tables. (C) A process of ensuring that data is stored in a single place and that all references to that data point to the same place. (D) All of the above.
Answer: (D)
Q2. What is the difference between a first normal form (1NF) database and a second normal form (2NF) database?
A 1NF database is a database where all attribute values are atomic and non-repeating. A 2NF database is a database that is in 1NF and all non-key attributes are fully functionally dependent on the primary key.
Q3. What is the difference between a second normal form (2NF) database and a third normal form (3NF) database?
A 2NF database is a database that is in 1NF and all non-key attributes are fully functionally dependent on the primary key. A 3NF database is a database that is in 2NF and all non-key attributes are not transitively dependent on the primary key.
Q4. What are some of the benefits of database normalization?
Database normalization offers a number of benefits, including:
- Reduced data redundancy: Normalization helps to eliminate duplicate data from the database, which can save storage space and improve performance.
- Improved data integrity: Normalization helps to ensure that the data in the database is accurate and consistent.
- Increased flexibility: Normalization makes it easier to update and maintain the database.
- Enhanced security: Normalization makes it more difficult to unauthorized users to access and modify data.
Q5. What are some of the challenges of database normalization?
Database normalization can be a complex and time-consuming process. It can also make the database more difficult to design and understand.