Data Isolation and Program Data Dependency
Data Isolation:
The data in file processing system is stored in various files; it becomes very difficult to write new application, programs to retrieve the appropriate data. Suppose that student emails are stored in “Students” file and fee information is stored in “Fee” file. To send an email message to inform a student that the date for fee payment is over, you need data from both files. In file processing system, it is difficult to generate such type of list from multiple files.
Program Data Dependency:
Program data dependency is a relationship between data stored in files and the specific program required to update and maintain those files. With file processing system, application programs are developed according to a particular file format. If the format of the underlying tile is changed, the application program also needs to he changed accordingly. For example, if there is any change in the length of postal code, it requires change in the program. Such changes may he costly to implement.
