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Unit III: Database concepts and the Structured Query Language
9 DATABASE CONCEPTS AND
THE STRUCTURED QUERY
LANGUAGE
Chapter Outline
9.1 Introducing DBMS 9.2 Relational Data Model
9.3 Structured Query Language (SQL) 9.4 Data Types
9.5 SQL Statements and Functions 9.6 DISTINCT clause
9.7 ORDER By Clause 9.8 BETWEEN Operator
9.9 IN Operator 9.10 IS Operator
9.11 LIKE Operator
Introduction
We have been dealing with data in all aspects of life much before computers' advent. Railways, healthcare systems,
education, defence, and various businesses deal with vast amounts of data that need to be stored and managed
efficiently. Since organisational decisions depend heavily on the timely availability of information, the companies felt
the need for a system that could handle the data efficiently. Database Management System (DBMS) help store related
data and manage it through application programs. Structured Query Language (SQL) is the most popular language for
database creation and management. In this chapter, we shall study the basic concepts of DBMS.
9.1 Introducing DBMS
Data are raw facts. We often need to extract useful information from the data that forms the basis of decision-making.
For example, consider a class of 50 students who have indicated their preference for the game they want to play out of
the four games available: basketball, badminton, cricket, and table tennis. While individual choices are important, the
school administration would like to know how many students want to play each game. Thus, summary information that
cricket, badminton, basketball, and table tennis are the choices of 23, 10, 9, and 8 students, respectively, will be helpful
to the school for planning purposes. Further, the preceding information concludes that cricket is the most popular game.
Thus, we have obtained beneficial information by processing the raw data about individual student preferences. Fig 9.1
illustrates the relationship between data and information.
0010110010110100101100
01111100101101001011111 Welcome
0010000010110100101100 to
00101111101101001011111 Informatics Practices
0010110010110000101100
00101100110101001011111
Data Process Information
Fig 9.1: Relationship between data and information
Database Concepts and the Structured Query Language 231

