Data redundancy: In the case of data redundancy, the same data fields appear in many different files and often in different formats or example, a course grades file and a tuition billing file may both contain a student’s ID number, name, address, and telephone number. If data fields are repeated often in different files, storage space is wasted.
Computers were placed in commercial use in 1954, when General Electric Purchased a UNIVAC (Universal Automatic Computer) for its research division. At first, the processing performed was straightforward.
Applications software programs tended to be sequentially organized and stored in a single file on magnetic tape that contained all the elements of data required for processing. The term file management system was coined to describe this traditional approach to managing business data and information. However, file management systems did not provide the user with an easy way to group records within a file or to establish relationships among the records in different files. As disk storage became more cost-effective and its capacity grew, new software applications were developed to access disk-based files. The need to access data stored in more than one file was quickly recognized and posed increasingly complex programming requirements. The most serious problems of file management systems involve:
Updating files and maintaining data integrity: Data redundancy creates a problem when it comes to updating files. When a data field needs to be changed- for example, student address-it must be updated in all the files in which it occurs. This is a tedious procedure. If some files are missed, data will be inconsistent. Inconsistent data leads to inaccurate information. When data is inconsistent, data integrity is not maintained and reports will be produced with erroneous information. Data integrity generally refers to the general quality of the data-that is to its accuracy and consistency.
Lack of program and data independence: Another limitation of file management systems has to do with the lack of program independence and data independence. This lack of independence means that programs must be written by programs must be written by programmers to use a specific file format. This process takes a programmer a large amount of time and costs a company a great deal of money for program and data file maintenance. Program and data independence means that files are organized so that business programs can be written to access data from the multiple files stored in the database. A change can be made in the program without having to change the data and vice versa.
To deal with these problems and the ever-growing demands for a flexible, easy-to-use mechanism for managing data, the concept of a database was developed.