Problems Caused By Redundancy in DBMS

In this post, we will see what are the problems caused by redundancy in dbms.

Data is one of the most important aspects of any business or organization. If you consider schools or colleges, they store information of students, if you consider organization which employs people to work or accomplish a task, they store information of employees.

Redundancy means storing the same field information more than once unnecessarily in a database is called as Redundancy.

Let’s take an example of order management system.

Below is the Customer table

CustomerNo FirstName LastName City State
551 Vikas Malhotra Varanasi Uttar Pradesh
552 Keerti Mahajan Nagpur Maharashtra
553 Harish Reddy Warangal Andhra Pradesh

Below is the Orders table

InvoiceNo InvoiceDate CustomerNo FirstName City
111 12/1/2019 551 Vikas Varanasi
112 12/1/2019 551 Vikas Varanasi
113 06/1/2019 552 Keerti Nagpur
114 06/1/2019 552 Keerti Nagpur
115 01/1/2019 553 Harish Warangal


If you watch both the tables closely, FirstName and LastName are stored in more than one table i.e. in both Customer and Orders table. Let’s consider If CustomerNo 551 i.e. Vikas changes his city from Varanasi to Lucknow, and then we update the City details in Customer table to Lucknow. But the city details in Orders table will still be Varanasi and not have the most recent updated data. In this case the data needs to be updated in multiple places which can be time consuming in case of large database.

One of the problems caused by redundancy is that there is a waste of space as we are storing data at multiple places. Another problem is that multiple updations of same data are required in multiple tables. The third problem that may occur is that the database might become inconsistent if the values are different at different places.

That’s end of our post on Problems Caused By Redundancy in DBMS

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