Database System Versus File System
Consider part of a savings-bank enterprise that keeps information about all customers and savings accounts. One way to keep the information on a computer is to store it in system files. To allow users to manipulate the information, the system has a number of application programs that manipulate the files including
A program to debit or credit an account
A program to add new account
A program to find the balance of an account
A program to generate monthly statements
System programmers wrote these application programs to meet the needs of the bank,
New application programs added to the system as the need arises.
For example, suppose the savings bank decided to offer checking account. As a result, the banks create new permanent files that contain information about all the checking accounts maintained in the bank, and it may have to write new application programs to deal with situations that do not arise in savings account, such as overdrafts. Thus, as time goes by, the system acquires more files and more application programs.
The typical file processing system stores permanent records in various files and it needs different application program to extract records from, add records to the appropriate files. Before database management system came along, organizations usually stored information in such systems files.
Keeping organizational information in a file-processing system has a number of major disadvantages.
The description of the data and the logic for accessing those data built into each individual application program, thus the program is dependent on the data files. Any change to the data file requires modifying or rewriting the application program. In contrast, in the database approach all data descriptions are stored separately from application program.
UNCONTROLLED DATA REDUNDANCY
Since different programmers create the files and application programs over a...
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