Advantage of DBMS

Answer 1

DataBase Management System (DBMS) is a software package that allows data to be effectively stored, retrieved and manipulated and the data stored in a DBMS packege can be accessed by multiple users and by multiple application programs like (SQL Server, Oracle, Ms-Access) .

The advantages of DBMS

1. It represents complex relationships among different data items.
2. Keeps a tight control on data redundancy.
3. Enforces user defined rules to ensure the integrity of data in a table form.
4. Maintains data dictionary for the storage of information pertaining to data fields and data manipulation.
5. Ensures that data can be shared across all applications.
6. Enforces data access authorization.
7. Has an automatic intelligent backup and recovery procedure of data.
8. Has different interfaces through which users can manipulate data.

Advantages of using a DBMS

There are three main features of a database management system that make it attractive to use a DBMS in preference to more conventional software. These features are centralized data management, data independence, and systems integration.

In a database system, the data is managed by the DBMS and all access to the data is through the DBMS providing a key to effective data processing. This contrasts with conventional data processing systems where each application program has direct access to the data it reads or manipulates. In a conventional DP system, an organization is likely to have several files of related data that are processed by several different application programs.

In the conventional data processing application programs, the programs usually are based on a considerable knowledge of data structure and format. In such environment any change of data structure or format would require appropriate changes to the application programs. These changes could be as small as the following:

1. Coding of some field is changed. For example, a null value that was coded as -1 is now coded as -9999.
2. A new field is added to the records.
3. The length of one of the fields is changed. For example, the maximum number of digits in a telephone number field or a postcode field needs to be changed.
4. The field on which the file is sorted is changed.

If some major changes were to be made to the data, the application programs may need to be rewritten. In a database system, the database management system provides the interface between the application programs and the data. When changes are made to the data representation, the metadata maintained by the DBMS is changed but the DBMS continues to provide data to application programs in the previously used way. The DBMS handles the task of transformation of data wherever necessary.

This independence between the programs and the data is called data independence. Data independence is important because every time some change needs to be made to the data structure, the programs that were being used before the change would continue to work. To provide a high degree of data independence, a DBMS must include a sophisticated metadata management system.

In DBMS, all files are integrated into one system thus reducing redundancies and making data management more efficient. In addition, DBMS provides centralized control of the operational data. Some of the advantages of data independence, integration and centralized control are:

1. Redundancies and inconsistencies can be reduced

   In conventional data systems, an organisation often builds a collection of application programs often created by different programmers and requiring different components of the operational data of the organisation. The data in conventional data systems is often not centralised. Some applications may require data to be combined from several systems. These several systems could well have data that is redundant as well as inconsistent (that is, different copies of the same data may have different values). Data inconsistencies are often encoutered in everyday life. For example, we have all come across situations when a new address is communicated to an organisation that we deal with (e.g. a bank, or Telecom, or a gas company), we find that some of the communications from that organisation are recived at the new address while others continue to be mailed to the old address. Combining all the data in a database would involve reduction in redundancy as well as inconsistency. It also is likely to reduce the costs for collection, storage and updating of data.

2. Better service to the Users

   A DBMS is often used to provide better service to the users. In conventional systems, availability of information is often poor since it normally is difficult to obtain information that the existing systems were not designed for. Once several conventional systems are combined to form one centralised data base, the availability of information and its up-to-dateness is likely to improve since the data can now be shared and the DBMS makes it easy to respond to unforseen information requests.

   Centralizing the data in a database also often means that users can obtain new and combined information that would have been impossible to obtain otherwise. Also, use of a DBMS should allow users that do not know programming to interact with the data more easily.

   The ability to quickly obtain new and combined information is becoming increasingly important in an environment where various levels of governments are requiring organisations to provide more and more information about their activities. An organisation running a conventional data processing system would require new programs to be written (or the information compiled manually) to meet every new demand.

3. Flexibility of the system is improved

   Changes are often necessary to the contents of data stored in any system. These changes are more easily made in a database than in a conventional system in that these changes do not need to have any impact on application programs.

4. Cost of developing and maintaining systems is lower

   As noted earlier, it is much easier to respond to unforseen requests when the data is centralized in a database than when it is stored in conventional file systems. Although the initial cost of setting up of a database can be large, one normally expects the overall cost of setting up a database and developing and maintaining application programs to be lower than for similar service using conventional systems since the productivity of programmers can be substantially higher in using non-procedural languages that have been developed with modern DBMS than using procedural languages.

5. Standards can be enforced

   Since all access to the database must be through the DBMS, standards are easier to enforce. Standards may relate to the naming of the data, the format of the data, the structure of the data etc.

6. Security can be improved

   In conventional systems, applications are developed in an ad hoc manner. Often different system of an organisation would access different components of the operational data. In such an environment, enforcing security can be quite difficult.

   Setting up of a database makes it easier to enforce security restrictions since the data is now centralized. It is easier to control who has access to what parts of the database. However, setting up a database can also make it easier for a determined person to breach security. We will discuss this in the next section.

7. Integrity can be improved

   Since the data of the organization using a database approach is centralized and would be used by a number of users at a time, it is essential to enforce integrity controls.

   Integrity may be compromised in many ways. For example, someone may make a mistake in data input and the salary of a full-time employee may be input as $4,000 rather than $40,000. A student may be shown to have borrowed books but has no enrolment. Salary of a staff member in one department may be coming out of the budget of another department.

   If a number of users are allowed to update the same data item at the same time, there is a possiblity that the result of the updates is not quite what was intended. For example, in an airline DBMS we could have a situation where the number of bookings made is larger than the capacity of the aircraft that is to be used for the flight. Controls therefore must be introduced to prevent such errors to occur because of concurrent updating activities. However, since all data is stored only once, it is often easier to maintain integrity than in conventional systems.

8. Enterprise requirements can be identified

   All enterprises have sections and departments and each of these units often consider the work of their unit as the most important and therefore consider their needs as the most important. Once a database has been set up with centralised control, it will be necessary to identify enterprise requirements and to balance the needs of competing units. It may become necessary to ignore some requests for information if they conflict with higher priority needs of the enterprise.

9. Data model must be developed

   Perhaps the most imporrant advantage of setting up a database system is the requirement that an overall data model for the enterprise be built. In conventional systems, it is more likely that files will be designed as needs of particular applications demand. The overall view is often not considered. Building an overall view of the enterprise data, although often an expensive exercise, is usually very cost-effective in the long term.

Answer 2

1.4 ADVANTAGES OF USING DBMS

1.Controlling Redundancy

In traditional file processing, every user group maintains its own files. Each group independently keeps files on their db e.g., students. Therefore, much of the data is stored twice or more. Redundancy leads to several problems :

duplication of effort

storage space wasted when the same data is stored repeatedly

files that represent the same data may become inconsistent (since the updates are applied independently by each users group).

We can use controlled redundancy.

2.Restricting Unauthorized Access

A DBMS should provide a security and authorization subsystem. Some db users will not be authorized to access all information in the db (e.g., financial data).

Some users are allowed only to retrieve data.

Some users are allowed both to retrieve and to update database.

3.Providing Persistent Storage for Program Objects and Data Structures

Data structure provided by DBMS must be compatible with the programming language's data structures. E.g., Object oriented DBMS are compatible with programming languages such as C++, SMALLTALK, and the DBMS software automatically performs conversions between programming data structure and file formats.

4.Permitting Inferencing and Actions Using Deduction Rules

Deductive database systems provide capabilities for defining deduction rules for inferencing new information from the stored database facts.

5.Providing Multiple User Interfaces

(e.g., query languages, programming languages interfaces, forms, menu-driven interfaces, etc.)

6.Representing Complex Relationships Among Data

7.Enforcing Integrity Constraints

8.Providing Backup and Recovery

(must provide facilities for recovering from hardware or software failures).