What Is Normalization?

What is normaliztion?

Normalization is the process of arranging and managing data. There are basically three forms which are quite sufficient to arrange and manage data

Below are the 3 normal forms,

1st Normal Form

Table is in first normal form when each column has single value.

Consider below table

Tblproduct

Productid	Name	Color	Supplier	mobilenumber	qty	Per unit price	price
P001	Prod1	Red	Supplier1	123456789	1	10	10
P002	Prod2	Red,Blue	Supplier2	986789123	1	10	10
P003	Prod3	Red,green	Supplier1	123456789	1	10	10

tblproduct will be considered in first normal form when every column in table has single value

Please have a look at column named color where you can find multiple values for the same column. In order to make this table in 1^st normal form we have to separate that column value as below

Tblproduct

Productid	Name	Color	Supplier	qty	Per unit price	price	mobilenumber
P001	Prod1	Red	Supplier1	1	10	10	123456789
P002	Prod2	Red	Supplier2	1	10	10	986789123
P002	Prod2	Blue	Supplier2	1	10	10	986789123
P003	Prod3	Red	Supplier1	2	10	20	123456789
P003	Prod3	Green	Supplier1	3	10	30	123456789

Now tblproduct is in first normal form.

Second Normal form

Table can be said to be in 2nd normal form when it satisfies condition/rules of first normal form. And every column in table should be dependant on primary key of table. Below is second normal form of tblproduct.

Now we are going to divide tblproduct into 3 different entities

tblproduct

Productid	Name	Supplierid	Qty	Per unit price	price	mobilenumber
P001	Prod1	1	1	10	10	123456789
P002	Prod2	2	1	10	10	986789123
P003	Prod3	1	1	10	10	123456789

tblcolor

Colorid	Name
1	Red
2	Blue
3	Green

tblsupplier

Supplierid	Name
1	Supplier1
2	Supplier1

Below is a mapping table for color of products.

tblproductcolormapping

ProductId	Colorid
P001	1
P002	1
P002	2
P003	3
P003	1

Third Normal Form

Table is said to be in 3^rd Normal form when it is in compliance with all the rules of second normal form.

And there should not be a column which is directly dependant on non-key field .

By looking at tblproduct, we can see mobile number is not related to product and price is also dependant on qty and per unit price column so we need to remove these dependancies. Price is calculative column so we can calculate it on the fly by multiplying qty and per unit price. The structure of tables will be like below if tblproduct is in 3^rd normal form

Productid	Name	Supplierid	qty	Per unit price
P001	Prod1	1	1	10
P002	Prod2	2	1	10
P003	Prod3	1	1	10

Colorid	Name
1	Red
2	Blue
3	Green

Supplierid	Name	mobilenumber
1	Supplier1	123456789
2	Supplier1	986789123

Below is a mapping table for color of products.

ProductId	colorid
P001	1
P002	1
P002	2
P003	3
P003	1