SQL at SQL Book

Introduction to SQL

The articles in this section are aimed at giving a quick but thorough introduction to SQL, what it is, how it can be used and an introduction to the main 'bread and butter' commands.

• Introduction to SQL

  SQL stands for Structured Query Language. Structured Query Language is a standard computer language that is used to communicate with databases.

• Using the SQL SELECT Statement

  In this multi part series on the SQL SELECT statement we will start off demonstrating the SELECT statement in its simplest form and then building on this we will demonstrate additional aspects of the SELECT statement.

• The SQL WHERE Clause

  In this article we will see how the WHERE clause can be used to select specific rows from the table that match certain specified criteria or conditions.

• Using the SELECT INTO statement to create backup and archive copies of data

  This article identifies common uses for the SELECT INTO statement and gives syntax definition and code examples to demonstrate the statements potential uses.

• SQL UNION and UNION ALL

  The SQL UNION command can be used to combine the output from 2 or more SELECT statements into 1 resultset. This article explains the syntax and rules of the UNION command and gives real world examples of it in use.

• SQL LIKE - flexible string matching

  The SQL LIKE operator is often used in the WHERE clause to find string matches on part of a column value by using a wildcard character. Article include examples, syntax and tips.

• Using SQL DISTINCT

  Find out how to use the SQL DISTINCT command to return only unique rows. Article includes the syntax and real world example of it in use.

• SQL Inner Join - examples and explanations

  SQL INNER JOIN - accessing data from more than one table in one query at SQLBook.com

• The SQL Outer Join - return all specified rows from one of the two tables in the join

  The SQL Outer Join can be used to define a relationship between columns in two different tables and will return all rows from one of the tables whether a related record in the other table exists or not.

• SQL Merge - a standard SQL statement for more elegant queries

  The SQL Merge statement is an official SQL standard (introduced in SQL: 2003 - the 5th version of the SQL standard) that enables UPDATE, INSERT and DELETE statements to be combined into one easy to use statement.

• The DROP TABLE IF EXISTS SQL statement explained with examples and tips

  Learn how to use the DROP TABLE IF EXISTS SQL statement to help delete your database tables and maintain your desired database object structure.

• DROP TABLE in SQL - the complete guide to deleting tables

  What is DROP TABLE in SQL? Learn how to delete tables safely and how this can impact other objects in your database.

Securing your SQL applications

A hackers prime target is often a database of some kind and they can use SQL commands and other security vunerabilities to gain access to your database. Learn how to secure your databases in these articles.

• SQL Injection Attacks - are your databases secured?

  In this 2 part series we will demonstrate what SQL injection is, how the hacker can use it against you and how you can protect yourself by employing a number of different strategies in your database and the design of your front end applications.

• Defending against SQL Injection attacks

  In this article we will look at the methods you can secure your database and front end applications to protect yourself from SQL Injection hacks.