Anomalies in DBMS
"What does anomaly mean?". The dictionary defines anomaly as “an abnormality.”
Ideally, a field value change should be made in only a single place.
Data redundancy, however, fosters an abnormal condition by forcing field value changes in many different locations.
Anomalies in DBMS develops when not all of the required changes in the redundant data are made successfully.
The Different Anomalies in DBMS:
1. Anomalies in DBMS: Update Anomalies
If agent Leah F. Hahn has a new phone number, that number must be entered in each of the CUSTOMER file records in which Ms. Hahn’s phone number is shown. In this case, only three changes must be made. In a large file system, such a change might occur in hundreds or even thousands of records. Clearly, the potential for data inconsistencies is great.
2. Anomalies in DBMS: Insertion Anomalies
If only the CUSTOMER file existed, to add a new agent, you would also add a dummy customer data entry to reflect the new agent’s addition. Again, the potential for creating data inconsistencies would be great.
3. Anomalies in DBMS: Deletion Anomalies
If you delete the customers Amy B. O’Brian, George Williams, and Olette K. Smith, you will also delete John T. Okon’s agent data. Clearly, this is not desirable.
Other Important DBMS Questions
