Database Anomalies
Database anomalies are the problems in relations that occur due to redundancy in the relations. These anomalies affect the process of inserting, deleting and modifying data in the relations. Some important data may be lost if a relation is updated that contains database anomalies. It is important to remove these anomalies in order t perform different processing on the relations without any problem.
Types of Anomalies
Different types of database anomalies are as follows:
1. Insertion Anomaly
The insertion anomaly occurs when new record is inserted in relation. In this anomally user cannot insert a fact about an entity until he has an additional fact about another entity.
2. Deletion Anomaly
The deletion anomaly occurs when a record is deleted from the relation. In this anomaly, the deletion of facts about an entity automatically deletes the fact of another entity.
3. Modification Anomaly
The modification anomaly occurs when the record is updated in the relation. In this anomaly, the modification in the value of specific attribute requires modification in all records in which that value occurs.
What Is Partial Dependency? How Does Partial Dependency Affect A Relation?
Partial dependency
A type of dependency in which one or more non-key attributes are functionally dependent on a part of primary key is called partial dependency.