Book Image

The SQL Workshop

By : Frank Solomon, Prashanth Jayaram, Awni Al Saqqa
Book Image

The SQL Workshop

By: Frank Solomon, Prashanth Jayaram, Awni Al Saqqa

Overview of this book

Many software applications are backed by powerful relational database systems, meaning that the skills to be able to maintain a SQL database and reliably retrieve data are in high demand. With its simple syntax and effective data manipulation capabilities, SQL enables you to manage relational databases with ease. The SQL Workshop will help you progress from basic to advanced-level SQL queries in order to create and manage databases successfully. This Workshop begins with an introduction to basic CRUD commands and gives you an overview of the different data types in SQL. You'll use commands for narrowing down the search results within a database and learn about data retrieval from single and multiple tables in a single query. As you advance, you'll use aggregate functions to perform calculations on a set of values, and implement process automation using stored procedures, functions, and triggers. Finally, you'll secure your database against potential threats and use access control to keep your data safe. Throughout this Workshop, you'll use your skills on a realistic database for an online shop, preparing you for solving data problems in the real world. By the end of this book, you'll have built the knowledge, skills and confidence to creatively solve real-world data problems with SQL.
Table of Contents (13 chapters)

The WHERE Clause Syntax

The WHERE clause is optional and can be added to any SELECT statement, usually after the FROM clause, as follows:

SELECT [COLUMNS LIST] 
FROM [TABLE NAME]
WHERE [CONDITION]
ORDER BY [COLUMN NAME] [ASC|DESC]

As you can see in the highlighted line, this statement starts with the WHERE keyword followed by a condition.

Conditions in SQL are logical operators that can be used for comparison. Condition operators are listed in the following table:

Figure 5.3: Conditional operators in SQL

These operators can be used to compare two fields/values to achieve the desired results.

Note

The compared fields or values must be of the same data type for the statement to be successful.

A simple implementation of a WHERE clause is as follows:

USE studentdemo; 
SELECT *
FROM Student;

The sample Student table looks like this:

Figure 5.4: Sample student table

Using the Student table of the StudentDemo database...