Data inconsistency is a condition that occurs between files when similar data is kept in different formats in two different files, or when matching of data must be done between files. As a result of the data inconsistency, these files duplicate some data such as addresses and names, compromising data integrity.
The duplicated data, also known as the redundant data, creates unreliable information because the chances of having a value changed in one file are high, but on the other file the value remains the same. This condition of inconsistency is often experienced when using the traditional file processing, and it is very expensive and difficult to rectify such inconsistencies.
For example, if a hospital is using the traditional file processing, changing the address of a patient will cause changes in several other files because they are kept separately. Inevitably, a case would arise where the address of the patient will be correct in one record and different in another. In addition, the billing office will be required to consult two different records to get satisfactory information concerning the status of a patient’s account, leading to reduced data security. The solution to this problem of inconsistency is the use of database, which is an integrated collection of files.