Explain what is meant by an update anomaly.?

An update anomaly occurs in a database when changes to data are not consistently applied across all instances of that data, leading to potential inconsistencies. For example, if a customer's address is stored in multiple records, updating it in one location but not others can result in different addresses being associated with the same customer. This situation typically arises in poorly designed databases, particularly those that aren't normalized, where data redundancy exists. As a result, maintaining data integrity becomes challenging, and the reliability of the database is compromised.