Anomalies in DBMS

Broadly, we have three types of anomalies that will occur when the database is not normalized. These are the insertion, update, and deletion anomalies. Let's consider each one of them with an example.

For example, suppose a company stores employee details in a table named employee that has four attributes: emp_id to store the employee's id, emp_name to store the employee's name, emp_address to store the employee's address, and emp_dept to store the department details (where the employee works). At the initial stage, the table will look like this:

emp_id	emp_name	emp_address	emp_dept
101	Roger	Texas	D001
101	Roger	Texas	D002
123	Martin	Ohio	D890
166	George	New York	D900
166	George	New York	D004

As you can see, the preceding table is not normalized. We will start to see the following problems when a table is not normalized:

• Update anomaly: In the preceding table...