THE CONCEPT OF DBMS AND RDBMS

Database concept

A database is an integrated collection of well-defined data and information, centrally controlled in all aspects, created and stored in a typical structure for an organization. In an organization, the database could be one or more depending upon the needs and operations of the organization. The data structure and its storage should be such that it facilitates, shareability, availability, resolvability, and integrity of the data. The database separates a design of the information system from the data design and its management.

Conventionally, in an information system, the information system, the information is obtained by developing the system and integrating them. This calls for breaking the system into various subsystems and developing the information systems independently. In this approach, each system will have its master files and transaction files. They have to be processed separately at different times, depending upon the needs and schedules. The file layouts and access methods could be different in different systems. Therefore, the files are updated at different times. This approach does affect the quality of the information across all the systems due to various reasons.

The data in many systems are common, and there is a repetition of data storage in various systems. This is called data redundancy. The redundancy of data current and the same in all the files, the management is complex in such a situation. The reports generated out of such files show discrepancies in the information. Since the data files are different for the different need to be created at different times. Transaction updating is also carried out at different times. It requires the increase of a magnetic media for storage because the systems are developed independently. The redundancy causes lack of integrity and inconsistency of the data in various files. The following are the main causes which gave birth to the database:

1.       The data redundancy and inconsistency: since the files are created for each application differently, the files are likely to have different formats and data design as they are created by different designers and programmers over in a period of time. Hence, the same data record may be present in more than one file, the creation, updating, and deletion of which is managed by a different programmer. Over a period of time, a situation arises when the data is redundant and inconsistent, due to the changes not being incorporated simultaneously in all the applications and in all the files.

2.       Difficulty in access to the data: in conventional system design, the file structure is consistent with the specific information needs. If the information needs change, gaining access to the data present in different files to satisfy the revised need, requires writing the necessary application programs every time. This is difficult and very time-consuming at critical times.

3.       Security problems: the file systems have a limitation of controlling the access to the record causing insecurity with respect to the information. Since the application programs are written from time to time and again, it is difficult to enforce discipline on the security constraints across all the applications.

4.       The integrity of the data: in a file system, it is difficult to maintain the integrity of the data across the application. The integrity rules are added when the programs are written. If any changes in the rules occur, it is very difficult to ensure that it is affected across the files in all the applications.

5.       To eliminate the above problems, the database approach is suggested. The database is designed independently of its use for the application. In other words, the user of the database should view the data in the database as on which he can develop his systems separately. Since the database matching his needs is common, the problems of redundancy and inconsistency are eliminated.

The advantages of the database approach are as follows:

·         The application system can be developed independently of the database

·         Any report using the information will not be inconsistent

·         Easy access to the database as per needs

·         The data validation and updating will be one and same for all

·         The data is shared by all the users

·         The data security and privacy can be managed and ensured because data entry in the database occurs once only and is protected by the security measures

·         Since the database is a storage of the structured i9nformation, the queries can be answered fast by using the logic of the data structures

RDBMS

The organization needs that MIS would give them a ‘competitive strength’. Simply computerizing the back office or the front office operations is no lo0nger sufficient. The need is to handle an on-line operation, mission, control applications and exercise the operational and management control. The need demands a tool to effectively handle both the transaction processing and the decision processing requirements. It also requires the capability of dealing with hundreds of users who are using and updating a large database. The need further demands the use of multiple databases residing on the hardware platforms situated at different location-nearby sites and remote site. The decision-making is required more in a real-time environment where the decision-making process, right from the problem definition to the solution, needs to be handled quickly. The business environment is distributed and decentralized requiring real-time resources (hardware, software, data, information) sharing with a complex data flow. All this demands the RDBMS which can serve both the decision support and the transaction processing requirements.

The latest RDBMS systems have two sub-systems or parts. One deals with the data management and transaction processing which is independent of its applications in the information processing. The second part provides a set of tools for developing and utilizing the online application for decision support. This is handled by the client-server architecture which separates the data management functions from its application. The data management function is handled by the server and the applications are handled by the client. The server centrally enforces all integrity, security and autonomy rules and the client (user) makes use of the database over the network of heterogeneous hardware.

The latest trend in the information technology is to make the end user computing simple, easy to understand and easy to use. The concept is extended to the system analyst and programmer, where the RDBMS provides the tools, saving, development and processing time. It allows the business rules of the organization, standard transactions and queries to be programmed once and makes them available to all the users and developers as a stored procedure in the data dictionary. These stored procedures can be nested to develop an application. These procedures are both, reusable and sharable and are developed using the standard SQL. The RDBMS is also capable through the interface to handle the data sources from the other database and application tools developed on different operating systems.

The modern RDBMS system operates under the client-server environment as against the traditional master-slave environment. In the traditional DBMS system, a transaction is processed in the database, i.e. the creation, validation and checking the transaction integrity logic. This is done for each transaction separately based on the procedures developed forced transaction for validity and integrity checks. In the modern RDBMS system, the third step of the integrity checking is done through a stored procedure common to all types of transaction.

Modern RDBMS allows high-level security by providing various tools to the system administrators, the database owners and the users to grant and revoke permission to the specified users or a group of users on the specified tables, view, columns, stored procedures, and commands. In the traditional DBMS system, the data was required to store in different databases In line with the security levels. While in the modern RDBMS system multiple security is taken care of by one integrated DBMS.

The latest RDBMS allows online maintenance, rapid recovery, and software-based fault tolerance. These features ensure the availability of the database round the clock as the database maintenance is possible online when the system is in use. The maintenance activity consists of the following tasks:

1.       Backup

2.       Diagnostic

3.       Integrity changes

4.       Recovery

5.       Design changes

6.       Performance tuning

The rapid recovery feature also the system administrator to provide a ‘time’ to go back for recovery of the data if the system fails due to the power failure or network crash. Based on this, time systems automatically go and collect all the changes and writes the risk.

The modern RDBMS, unlike the traditional DBMS, handles the distributed heterogeneous data sources, software environment, and hardware platforms. The system is open RDBMS. The modern business activity using the multiple hardware-software platforms, such a business enterprise has multiple databases residing at various locations. The information needs call for the unification and coordination of these databases. The data would get updated in distributed access to the distributed data.

RDBMS allows communication at the database level and performs in a unified manner as a single entity through the updates, and processing would take place at the respective distributed locations. This is achieved through a software interface across the organization. Since the environment is distributed, it calls for distributed integrity control and autonomy to perform. The distributed integrity control is achieved through the stored procedures is made to protect the database from a remote external update or processing to maintain the autonomy which would be affected by the unauthorized update from remote locations.

The characteristics of modern RDBMS includes hardware independence, software independence, workability under a client-server architecture, a control feature of integrity, security and autonomy and built-in communication facilities to achieve and open the system features for the MIS. It, therefore, provides a very efficient and effective tool to a skillful designer, developer, and user for handling the information needs of the business enterprise.