- Normalization is the process of reorganizing data in a database. They have two basic requirements they are:
- No redundancy of data.
- Logical as data dependencies.
- To normalize a database, we divide the database into tables and establish relationships between the tables.
- Database normalization can essentially be defined as the practice of optimizing table structures.
- Optimization is accomplished as a result of a thorough investigation of the various pieces of data that will be stored within the database, in particular concentrating upon how this data is interrelated.
Types of Normalization
- 1NF
- 2NF
- 3NF
- BCNF
- 4NF
- 5NF
First Normal Form (1NF)
- The First Normal Form should be following some rules in table,
- It should only have single(atomic) valued attributes/columns.
- Values stored in a column should be of the same domain
- All the columns in a table should have unique names.
- And the order in which data is stored, does not matter.
Second Normal Form (2NF)
- For a table to be in the Second Normal Form,
- It should be in the First Normal form.
- And, it should not have Partial Dependency.
Third Normal Form (3NF)
- A table is said to be in the Third Normal Form when,
- It is in the Second Normal form.
- And, it doesn’t have Transitive Dependency.
Boyce and Codd Normal Form (BCNF)
- Boyce and Codd Normal Form is a higher version of the Third Normal form. This form deals with certain type of anomaly that is not handled by 3NF. A 3NF table which does not have multiple overlapping candidate keys is said to be in BCNF.
- For a table to be in BCNF, following conditions must be satisfied:
- R must be in 3rd Normal Form and, for each functional dependency ( X → Y ), X should be a super Key.
Fourth Normal Form (4NF)
- A table is said to be in the Fourth Normal Form when,
- It is in the Boyce-Codd Normal Form.
- And, it doesn’t have Multi-Valued Dependency.
Fifth Normal Form (5NF)
- Fifth Normal Form (5NF), also known as project-join normal form (PJ/NF) is a level of database normalization designed to reduce redundancy in relational databases recording multi-valued facts by isolating semantically related multiple relationships.
- A relation R is in Fifth Normal Form (5NF) and only if the following conditions are satisfied simultaneously,
- R is already in 4NF.
- It cannot be further non-loss decomposed.
