Monday, April 16, 2001		Article

INFORMATION, they say, is power. We live in an environment that has an overflow of information, but not all of it translates into power unless it is available in an accessible way and makes sense.

In this information-hungry society, the term database has become a rather common word. While some people use the term database of an organisation to mean all data in the organisation, whether computerised or not, others use this term for the software that manages data. We will use this term as a collection of computerised information that is available to different people for various uses.

In the early days of computing, computers were mainly used for solving numerical problems. There were some tasks common to many problems that were performed using special subroutines. By the late fifties, storage, maintenance and retrieval of non-numeric data had also become very important. Due to these frequently occurring data-processing tasks like sorting, it became necessary to develop generalisd routines that performed most common tasks. In the early sixties, due to high costs of hardware, the use of general routines was not very popular. As the users demanded more extensive and flexible facilities for managing data, database management systems evolved from these generalised routines. Database technology underwent major changes during the seventies.

A database is nothing but a well-organised collection of data related in a meaningful way that can be accessed in different logical orders but stored only once. The data is, therefore, integrated, structured and shared. To access information from a database, you need a database management system. This is a collection of programs that enables you to enter, organise and select data from a database. Increasingly, the term database is being used for database management systems. Some commercially available database management systems are FOXPRO, ACCESS, ORACLE, INGRES and Sybase. Within these DBMS we write application programs that are the tools the client uses to add to, search or go through the database. These programs are according to the specific requirements of the user.

The database management system acts as an interface between users and the database in the same way as the salesperson works in a distributory system. A consumer specifies desired items to the salesperson at the counter. The salesperson presents the specified items to the consumer after retrieving them from the store. The consumer has no idea of where and how the items were stored in the huge stock of the store, but gets just what he needed from the efficient salesperson.

In the manual system of data storage, for example, addresses of your friends stored in an address book (the paper variety), matter has first to be systematically entered so that it can be searched for conveniently at a later time. Even if you have entered your addresses in an alphabetical order, you can face a problem later if you have to add a name in between. All this is difficult and time-consuming when done manually, as well as inefficient. This is where database systems step in and make our task easier by providing us utilities that help in retrieving data easily. By using such systems your data can automatically be arranged in any order you want and records belonging to any particular category or bit of data can be located instantly.

A good database management system (DBMS) would be one that can manage a large amount of data in a multiuser environment so that many users can access the same data concurrently. DBMS should be secure against unauthorised access and provide solutions for failure recovery. It provides portability so that you can use your applications on different operating systems with little or no modifications.

Apart from the above-mentioned benefits of sorting and searching, there are plenty of other useful features of DBMS.

Data independence: A significant advantage is data independence. A DBMS provides the interface between the application programs and the data. It handles the task of transformation of data wherever necessary. This helps avoid rewriting application programs every time the data is changed. This independence between the programs and the data is called data independence. For example, if we add a new record or a new field of information to an existing data, no change will have to be made in the application program, the DBMS will take care of that.

Centralised control: The data in conventional data systems is often not centralised. Some applications may require combining of data from several systems. These systems could well have data that is redundant as well as inconsistent. Combining all data in a database would involve reduction in redundancy as well as inconsistency. This, in turn, helps in reduction of costs of storage and updating of data. It also provides better services to users and up-to-date information.

Security: As database is centralised, security checks can also implemented, which helps in controlling who has access to which parts of the database. Only authorised people can access the database.

Data corruption risk: DBMS provides on-line access to the database to a large number of users. Because of this, when a database is used, an organisation may be exposed to additional risks as compared to a conventional paper-based data processing system. Apart from unauthorised access, there are also serious chances of users damaging the data as several of them are accessing it directly. There should and can be suitable controls provided.

Overwriting: A major threat to data integrity comes from different users attempting to update the same data at the same time. The database, therefore, needs to be protected against inadvertent changes.

Database systems are used by many organisations theses days. Some factors which should be considered before selecting a DBMS suitable for a particular organisation are: the application building capabilities; its data dictionary approach, i.e., the specification of various fields; data access — proprietary or through SQL (structured query language); integrity check approach; and security. Recovery and backup facilities can help the user in the case of data loss. The processing speed of database is also a factor that has to be kept in mind.

This was part I of a two-part series on database management. The next part will cover types and models of databases, and components and architecture of DBMS.