Data Redundancy Explained
Data redundancy occurs when the same piece of data is stored in two or more separate places. Suppose you create a database to store sales records, and in the records for each sale, you enter the customer address. Yet, you have multiple sales to the same customer so the same address is entered multiple times. The address that is repeatedly entered is redundant data.
How Does Data Redundancy Occur?
Data redundancy can be designed; for example, suppose you want to back up your company’s data nightly. This creates a redundancy. Data redundancy can also occur by mistake. For example, the database designer who created a system with a new record for each sale may not have realized that his design caused the same address to be entered repeatedly. You may also end up with redundant data when you store the same information in multiple systems. For instance, suppose you store the same basic employee information in Human Resources records and in records maintained for your local site office.