Database Normalization

DBMSDatabase

Database Normalization removes redundancy of data and anomalies in a poorly designed table. The process of normalization converts an unnormalized table in a normalized form.

Let us see what flaws are in an Unnormalized table i.e. why Normalization of Database is so crucial −

Redundancy of Data

Storing same data item multiple times is known as Data Redundancy.

Let us see an example −

We have an <Employee> table that has a field to store current address of Employees. Some of these employees are given a place to live by the company; therefore, they have the same address. The address will be repeated in the database −

Table 1.1

EmpID

EmpName

EmpAddress

E001
Emma
20, Street 17, Connecticut
E002
Jack
20, Street 17, Connecticut
E003
Adams
20, Street 17, Connecticut
E004
John
21, Street 17, Connecticut
E005
Rocky
21, Street 17, Connecticut


To solve it, store the employee address in a separate table and point in the <Employee> table.

Updation Anomaly

It occurs when you face issues while updating a table.

Deletion Anomaly

Let’s say the company decide to close a Department in the company, then the deletion of row would also lead the deletion of that employees data.

Insertion Anomaly

It occurs when you try to insert data in a record that does not exist.

Normalization removes all the above issues/ anomalies and gives you a normalized perfect database design that a database administrator love.

raja
Published on 03-Jul-2018 12:00:54
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