Normalization and Denormalization Normalization (1NF, 2NF, 3NF, BCNF) is a systematic approach for organizing data in a database to improve its integrity...
Normalization (1NF, 2NF, 3NF, BCNF) is a systematic approach for organizing data in a database to improve its integrity and efficiency.
1NF (First Normal Form):
A relation is in 1NF if every determinant (a column that determines a unique key for a row) is atomic (meaning it contains only one value).
An example of a 1NF relation would be a table with student information, where the student's name, address, and ID are the determinants.
2NF (Second Normal Form):
A relation is in 2NF if every determinant is fully dependent on the primary key.
This means that the determinant cannot be expressed as a function of any other columns except the primary key.
An example of a 2NF relation would be a table with student orders, where the student ID, order date, and total amount are the determinants.
3NF (Third Normal Form):
A relation is in 3NF if every determinant is fully dependent on the primary key and every non-key attribute is fully determined by the primary key.
This means that the entire determination of a row must be based on the primary key.
An example of a 3NF relation would be a table with student courses, where the student ID, course ID, and course name are the determinants.
BCNF (Boyce-Codd Normal Form):
A relation is in BCNF if every determinant is either a candidate key (a column that uniquely identifies a row) or a candidate key plus a non-key attribute (a column that determines the value of a determinant).
BCNF is the highest level of normalization, meaning that all attributes are either determinants or candidate keys.
Denormalization:
Denormalization is a technique for improving data integrity in a database by duplicating data from one table to another.
This can be done for various reasons, including:
To reduce data redundancy (avoiding storing the same data multiple times)
To improve performance by reducing the need to join multiple tables
To normalize a database to a higher level (e.g., 3NF or BCNF)
Examples:
A 1NF relation would be a table with student information, where the student's name and ID are the determinants.
A 2NF relation would be a table with student orders, where the student ID, order date, and total amount are the determinants.
A 3NF relation would be a table with student courses, where the student ID, course ID, and course name are the determinants.
By understanding and applying these different levels of normalization, data professionals can create databases that are more accurate, efficient, and easier to maintain