Chapter 3, Problem 3.32RQ

Program Plan Intro

SQL:

• SQL stands for “Structured Query Language”.
• The current version of SQL is “ANSI SQL – 92”.
• It contains constructs which are used to define and process database. They are executed using DBMS-supplied command prompt.
• SQL is not a programming language. It is text-based and it is also called as data sublanguage. In order to get SQL as a complete programming language, it should be included in scripting languages like Java, C#, and so on.

Display values from table:

The contents from the table can be viewed by using “SELECT” statement which comes under Data Manipulation Language (DML). Syntax to view the contents using asterisk (*) is as follows:

SELECT * FROM table_Name;

Grouping Rows:

SQL contains “GROUP BY” clause in order to group rows by common data. Though it is very powerful feature, it is hard to understand.

Syntax:

SELECT column_Name1 FROM table_Name GROUP BY column_Name2;

Example: Consider a table “student” contains two columns “student_Name” and “Department”. “GROUP BY” clause is used when there is a need to get the number of students from each department.

The query for this scenario is given as follows.

SELECT department, COUNT (department) FROM student GROUP BY department;

When the above query is executed, number of students from each department will be displayed.