2.1 WHAT ARE DATABASES AND DATABASE PROGRAMS?
A modern-day database is a structured collection of data stored in a computer. The term “struc-tured” implies that each record in the database is stored in a certain format. For example, all entries in a phone book are arranged in a similar fashion. Each entry contains a name, an address and a telephone number of a subscriber. This information can be queried and manipulated by database programs. The data retrieved in answer to queries becomes information that can be used to make decisions. The databases may consist of a single Table or related multiple Tables. The computer programs used to create, manage and query databases are known as database management systems (DBMSs). Just like databases, DBMSs vary in complexity. Depending on the needs of the user, one can use either a simple application or a robust program. Some examples of these programs were given earlier.
2.1.1 File Processing System
The file processing system (FPS) is a precursor of the integrated database approach. The records for a particular application are stored in a file. An application program is needed to retrieve or manipulate data in this file. Thus, various departments in an organization will have their own file processing systems with their own individual programs to store and retrieve data. The data in vari-ous files may be duplicated and is not available to other applications. This causes redundancy and may lead to inconsistency, meaning that various files that supposedly contain the same information may actually contain different data values. Thus duplication of data creates problems with data integrity. Moreover, it is difficult to provide access to multiple users with file processing systems without granting them access to the respective application programs, which manipulate the data in those files.
The FPS may be advantageous under certain circumstances. For example, if data is static and a simple application will solve the problem, a more expensive DBMS is not needed. For example, in a small business environment, you want to keep track of the inventory of the office equipment purchased only once or twice a year. The data can be kept in an Excel spreadsheet and manipulated with ease from time to time. This avoids the need to purchase an expensive database program and hire a knowledgeable database administrator. Before DBMSs became popular, data was kept in files, and application programs were developed to delete, insert or modify records in the files since specific application programs were developed by using specific data.
These programs lasted for months or years before modifications were necessitated by business needs.