What is the main cause of the update anomaly in unnormalized tables?

The main cause of the update anomaly in unnormalized tables is data redundancy. In unnormalized tables, the same piece of data can be stored in multiple rows. This redundancy means that when an update occurs, such as changing a customer's address, it has to be made in every instance where that address appears. If the update is not performed consistently across all instances, it can lead to inconsistencies in the database, where different rows reflect different addresses for the same customer. This inconsistency is what characterizes the update anomaly.

Data normalization is a process designed to eliminate redundancy and improve data integrity by organizing data into tables in such a way that each piece of information is stored only once. Data encryption pertains to securing data and does not directly relate to the structure or anomalies of databases. Data grouping refers to organizing data in a way that typically aids in reporting or querying but does not address the issues of redundancy that cause update anomalies. Therefore, data redundancy stands out as the primary cause of update anomalies in unnormalized tables.