Data+Redundancy

Data redundancy refers to data which is stored in a database that is not required. A good relational database design aims to reduce data redundancy.

Update, insertion and deletion anomalies are caused by data redundancy. By reducing data redundancy, these anomalies are also reduced.

The purpose of normalisation is to reduce data redundancy


 * Example**

In this example, we can see that there is data redundancy in the teacher column. Mrs Wallace, Mr Smith and Mr Petrie all appear twice in the table. Normalising the table will remove this data redundancy problem.