Database Normalization
Normalization:-
Normalization is a process to organize data in a database. Normalization is used to minimize the redundancy from a relation or set of relations. It is also used to eliminate undesirable characteristics like Insertion, Update, and Deletion Anomalies. It divides the larger table into a small table and joined (links) them using a primary and foreign key.
Types Of Normalization:-
There are mainly 4 types of normalization, these are as follows:
- First Normal Form (1NF):-
The 1NF forms state that the data contains the only atomic value. The data can not hold multiple values. Let’s see an example:
In the above example, we can see that there are multiple entries in the Knowledge column, It is not allowed in 1NF each cell contains only a single value like another table.
2. Second Normal Form (2NF):-
In the second normal form, The relation must be in 1NF form. The 2NF also says that relation does not contain any partial dependencies all the column depends on primary key if does not satisfy then make another small table. Let’s see an example:
In the above example, we can see that there are partial dependencies so we divide them into multiple small tables.
3. Third Normal Form (3NF):-
In Third Normal Form, A relation must follow 2NF as well as it does not contain any transitive partial dependencies. The 3NF form is used to remove duplicate data. The 3NF says that there are no transitive dependencies present in the data. Let us see an example:
In the above example, 1st table contains the columns Vendor-Id, Name, and Account_No which depend on ID means Id is a primary key as in 2nd table and the columns Bank_Code_No and Bank depend on Bank_Code_No means Bank_Code_No is also a primary key, so divide it into the small tables as shown in fig.
4. Boyce Codd normal form (BCNF):-
BCNF is the advanced form of 3NF, It says that the data must be in 3NF and for every data LHS has a super key let us see an example:
In the above example, The column Shop Type and Nearest Shop depends on the Person. That’s why Person is a super key and it is on the left side.
