Database Management Systems

1.1 Data,Information and Universe of Discourse

Have you ever noticed that people often say “I don’t have enough information” than saying “I don’t have enough data”. Can you justify this difference? Why people look for information rather than for data? Data are the known facts that can be recorded. They have an implicit meaning. That is data will rather have a meaning which is embedded or inherent to it. The meaning contained in data will help to infer additional facts or information.In the contrary, information is processed data which is presented in a form suitable for human interpretation and have an explicit meaning. Information helps to reveal trends or patterns and therefore supports decision making.

The existence, validity and applicability of data and information depend on the context in which it is considered. Information for one context can be a mere fact or data in another context.

Think about a university with related to the two queries given below.

Query 01: What is the total number of students register for the BIT Degree Programme during last 5 years?

Query 02: How many students have registered for degree programmes in the University during last 5 years?

When answering the query 01, you will have to get the number of students registered for each year (during last 5 years), and then get the total of those.

There the number of students registered in a given year would be a fact. The total number registered during last 5 years would be the information revealed using the known facts or data.

The Query 02, would need the numbers of students registered during last 5 years for each degree programme offered by the university. There, the total number of students registered for the BIT programme during last five years would be a fact, which will be used to infer the additional information required.

Hope this would help you to realize that information in one context can be data to another. That depends on the context and the complexity of the query which needs to be worked out.

Therefore, when working with data and databases, the relevance of data depends on the area of interest and the applicability, or the context within which the query is operated. This area of interest is called the ‘Universe if Discourse’ (UoD), or the ‘miniworld’. This reveals the reality of an organization or the environment, and some aspects of UoD will be reflected in the database.

Converting Data into Information

The conversion of data into information can be formerly discussed under five stages.

1. Acquisition: Collecting data

2. Storage: Storing data for future retrieval

3. Manipulation: Apply operations in terms of keeping them up to date, and also to infer required information

4. Retrieval: Refer the stored data and information

5. Distribution: Distribute data among necessary systems and parties.

The conversion stages can be considered in a cycle as the information derived and distributed by one system can be acquired as data for another.

Databases, Database Management Systems and Database Systems

A database can be thought of as a collection of related data which represents some Universe of Discourse. The database can be of any size depending on the Universe of Discourse. If the UoD is a particular organization, the database is designed to meet the needs of multiple users in that organization.Even though the term ‘Database’ is often discussed under computer related systems, a database can actually be generated and maintained either manually or in computerized form. A manual file which keeps records of the students of a university, and their marks will be a database which is kept manually.

Database Management System (DBMS) is a collection of programs, which is presented as general purpose software that enables users to create and maintain a database. It works as a shell which surrounds the database, and through which the interactions take place. Database Management Systems (DBMSs) facilitate the processes of defining, constructing, manipulating, and sharing databases.

Database Systems are the software systems composed of the database and the DBMS. In fact it is a computerized record keeping system prepared to be used in a particular organization or a context. The figure 1.1 shows how a simple Database System is organized.

Traditional File Processing Vs. Database Approach

In traditional file processing each new computer application is typically designed with its own set of data files. More often, each user defines and implements the files needed for a specific application used by that individual. This practice results in the same data to be redundant (same data is duplicated in several places). In fact, the same data item will be defined and stored over and over again as required by different users. Maintenance of the database becomes extremely difficult and inflexible, especially when changing the structure of a given item. In addition, if the same data item is duplicated in the system, the value of the item should be maintained the same in all the places. The failure to update accordingly would make the database inconsistent.