NCERT Class 11 Informative Practices Introduction To Structure Query Language

8.1 INTRODUCTION

We have learnt about Relational Database Management System (RDBMS) and purpose in the previous chapter. There are many RDBMS such as MySQL, Microsoft SQL Server, PostgreSQL, Oracle, etc. that allow us to create a database consisting of relations and to link one or more relations for efficient querying to store, retrieve and manipulate data on that database. In this chapter, we will learn how to create, populate and query database using MySQL.

8.2 STRUCTURED QUERY LANGUAGE (SQL)

One has to write application programs to access data in case of a file system. However, for database management systems there are special kind of programming languages called query language that can be used to access data from the database. The Structured Query Language (SQL) is the most popular query language used by major relational database management systems such as MySQL, ORACLE, SQL Server, etc.

SQL is easy to learn as the statements comprise of descriptive English words and are not case sensitive. We can create and interact with a database using SQL in an efficient and easy way. The benefit with SQL is that we don’t have to specify how to get the data from the database. Rather, we simply specify what is to be retrieved, and SQL does the rest. Although called a query language, SQL can do much more besides querying. SQL provides statements for defining the structure of the data, manipulating data in the database, declare constraints and retrieve data from the database in various ways, depending on our requirements.

In this chapter, we will learn how to create a database using MySQL as the RDBMS software. We will create a database called St ude nt At t e nda nc e (Figure 7.5) that we had identified in the previous chapter. We will also learn how to populate database with data, manipulate data in that and retrieve data from the database through SQL queries.

8.2.1 Installing MySQL

MySQL is an open source RDBMS software which can be easily downloaded from the official website https:// dev.mysql.com/downloads. After installing MySQL, start MySQL service. The appearance of mysql> prompt (Figure 8.1) means that MySQL is ready for us to enter SQL statements.

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