Question

Explain Data Anomalies.

Hint:

Anomalies are problems caused by storing the same information in too many places. Normalization is the process of organizing tables to reduce this redundancy and prevent anomalies.

Answer 1

Data anomalies are inconsistencies or data redundancy issues that can occur in a poorly designed database, typically one that has not been properly normalized. They lead to problems with data integrity. There are three main types:

Insertion Anomaly: The inability to add new data to the database because some other data is missing. (e.g., you can't add a new employee who hasn't been assigned to a department yet if the department ID is a required field).
Deletion Anomaly: The unintentional loss of data when another piece of data is deleted. (e.g., deleting the last employee in a department might delete the department itself).
Update Anomaly: Occurs when an update to a single piece of data requires multiple rows to be updated, and failing to update all of them leads to inconsistencies. (e.g., if an employee's address is stored in multiple places, you must update all instances).