Normalization is a process that is used to reduce the redundancy and dependency in a database. It is the process of organizing a database in such a way that it meets two main goals:
Minimize redundancy: Redundancy occurs when the same information is stored in multiple places in the database. This can lead to inconsistencies, as different copies of the same data may not be kept in sync. Normalization helps to eliminate redundant data and ensure that each piece of data is stored in only one place.
Minimize dependency: Dependency occurs when one piece of data depends on another piece of data. For example, if an employee’s salary is stored in a separate table from their personal information, the salary depends on the employee’s personal information. Normalization helps to minimize dependency by breaking up large tables into smaller ones and establishing relationships between them using keys.
There are several different types of normalization, each of which has its own set of rules for organizing a database. The most common types of normalization are:
First normal form (1NF): A table is said to be in 1NF if it satisfies the following rules:
Each column must contain a single value (i.e., no repeating groups)
The order of the columns does not matter
There must be a primary key (a unique identifier for each row)
Second normal form (2NF): A table is in 2NF if it is already in 1NF and all of its columns depend on the primary key. In other words, no column should depend on a part of the primary key; it should depend on the whole key.
Third normal form (3NF): A table is said to be in 3NF if it is already in 2NF and all of its columns are independent of each other. In other words, no column should depend on any other column except the primary key.
Boyce-Codd normal form (BCNF): A table is in BCNF if it is already in 3NF and every determinant (a column or set of columns that determines the value of another column) is a candidate key (a unique identifier that could potentially be used as the primary key).
Normalization is an important concept in database design because it helps to ensure that a database is organized in a way that is efficient, consistent, and flexible. It can also help to improve the integrity and security of a database by reducing the risk of data inconsistencies and unauthorized access.