Sunday, 29 July 2012

What are the advantages and disadvantages of using a DBMS instead of a file processing System?

The database approach offers a number of potential advantages compared to traditional file processing systems.
1. Program-Data Independence: The separation of data descriptions from the application programs that use the data is called Data independence. With the database approach. Data descriptions are stored in a central location called the repository. This property of database systems allows an organization’s data to change without changing the application programs
that process the data.
2. Data Redundancy and Inconsistency: In File-processing System, files having different formats and application programs may created by different programmers. Similarly different programs may be written in several programming languages. The same information placed at different files which cause redundancy and inconsistency consequently higher storage and access cost. For Example,the address and telephone number of a person may exist in two files containing saving account records and checking account records. Now a change in person’s address may reflect the saving account records but not any where in the whole system. This results the data inconsistency. One solution to avoid this data redundancy is keeping the multiple copies of same information, replace it by a system where the address and telephone number stored at just one place physically while it is accessible to all applications from this itself. DBMS can handle Data Redundancy and Inconsistency.
3. Difficulty in accessing Data: - In Classical file organization the data is stored in the files.Whenever data has to be retrieved as per the requirements then a new application program has to be written. This is tedious process.
4. Data isolation: - Since data is scattered in various files, and files may be in different formats, it is difficulty to write new application programs to retrieve the appropriate data.
5. Concurrent access: - There is no central control of data in classical file organization. So, the concurrent access of data by many users is difficult to implement.
6. Security Problems: - Since there is no centralized control of data in classical file
organization. So, security, enforcement is difficult in File-processing system.
7. Integrity Problem: - The data values stored in the database must satisfy certain types of consistency constraints. For example, the balance of a bank account may never fall below a prescribed amount. These constraints are enforced in the system by adding appropriate code in the various application programs. However, when new constraints are added, it is difficult to change the programs to enforce them. The problem is compounded when constraints involve several data items from different files.
8. Improved Data Sharing: - A database is designed as a shared corporate resource.
Authorized internal and external users are granted permission to use the database, and each user is provided one or more user views to facilitate this use. A user view is a logical description of some portion of the database that is required by a user to perform some task.
9. Increased Productive of Application Development: - A major advantage of the database approach is that it greatly reduces the cost and time of developing new business applications.
There are two important reasons that data base applications can often be developed much more rapidly than conventional file applications.
a) Assuming that the database and the related data capture and maintenance applications have already been designed and implemented, the programmer can concentrate on the specific functions required for the new application, without having to worry about file design or low-level implementation details.
b) The data base management system provided a number of high-level productivity tools such as forms and reports generators and high-level languages that automate some of the activities of database design and implementation.

Disadvantages:-

1. It occupies more amount of space. It is generic
2. More time they access data.
3. More complex and expensive hardware and software resources are needed.
4. Sophisticated security measures must be implemented to prevent unauthorized access of
sensitive data in online storage.

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