Database Reference
In-Depth Information
Chapter 1
DATABASE SYSTEMS
1.1 INTRODUCTION TO DATABASE SYSTEMS
Databases offer a convenient and powerful way to organize information.
Databases are not specific to computers. Examples of non-computerised databases are
phone book, dictionaries, almanacs, etc. Databases are designed to offer an organized
mechanism for storing, managing and retrieving information. Databases are probably
one of the most common uses of computers, and are available on just about every type
of computer. There are three main components to any database application: A method for
entering or editing data — usually data entry screens or import functions
A data storage mechanism — a way of storing the data on the computer A report gener-
ator to extract and interpret information from the stored data
1.1.2 Data
Data is collection of raw/ unorganized facts and figures. It simply exists and has
no significance beyond its existence. It can exist in any form, usable or not. It is always
need to be processed. Raw data may be collection of numbers, characters, images or it
can be acquired from many different sources. Data are typically the results of
measurements and can be the basis of symbols, graphs, images, or observations of a set
of variables. For example, age of students, the height of students, marks of students,
blood group students, is generally considered as “data”
1.1.3 Information
Valuable or useful data is called information
.
After processing, organizing and
presenting data in a given situation so as to make it useful, it becomes Information. For
example marks or height of a particular student may be considered as “information”,
Let us take another example, suppose that you want to know how you're doing in a particular
course. You have taken two 10-question multiple-choice tests. On the first test, you got ques-
tions 1, 3, and 4 wrong; on the second test, you did worse, missing items 5, 3, 6, and 9.
The items that you got wrong are merely datadata Unprocessed facts.—unprocessed facts.
What's important is your total score. You scored 70% on the first exam and 60% on the
second. These two numbers constitute information in formation Data that have been pro-
cessed or turned into some useful form.—data that have been processed, or turned into some
useful form.
1.2 CONCEPT OF A DATABASE
The simplest definition of a database is a collection of data items stored for later retrieval.
