Introduction Introduction
Welcome to PHP and MySQL Web Development. Within its pages, you will find distilled knowledge from our experiences using PHP and MySQL, two of the hottest web development tools around.
In this introduction, we cover
Why you should read this book
What you will be able to achieve using this book
What PHP and MySQL are and why they're great
What's changed in the latest versions of PHP and MySQL
How this book is organized
Let's get started.
Why You Should Read This Book
This book will teach you how to create interactive websites from the simplest order form through to complex, secure e-commerce sites or interactive Web 2.0 sites. What's more, you'll learn how to do it using open source technologies.
This book is aimed at readers who already know at least the basics of HTML and have done some programming in a modern programming language before but have not necessarily programmed for the Internet or used a relational database. If you are a beginning programmer, you should still find this book useful, but digesting it might take a little longer. We've tried not to leave out any basic concepts, but we do cover them at speed. The typical readers of this book want to master PHP and MySQL for the purpose of building a large or commercial website. You might already be working in another web development language; if so, this book should get you up to speed quickly.
We wrote the first edition of this book because we were tired of finding PHP books that were basically function references. These books are useful, but they don't help when your boss or client has said, "Go build me a shopping cart." In this book, we have done our best to make every example useful. You can use many of the code samples directly in your website, and you can use many others with only minor modifications.
What You Will Learn from This Book
Reading this book will enable you to build real-world, dynamic websites. If you've built websites using plain HTML, you realize the limitations of this approach. Static content from a pure HTML website is just that—static. It stays the same unless you physically update it. Your users can't interact with the site in any meaningful fashion.
Using a language such as PHP and a database such as MySQL allows you to make your sites dynamic: to have them be customizable and contain real-time information.
We have deliberately focused this book on real-world applications, even in the introductory chapters. We begin by looking at a simple online ordering system and work our way through the various parts of PHP and MySQL.
We then discuss aspects of electronic commerce and security as they relate to building a real-world website and show you how to implement these aspects in PHP and MySQL.
In the final part of this book, we describe how to approach real-world projects and take you through the design, planning, and building of the following projects:
User authentication and personalization
Shopping carts
Web-based email
Mailing list managers
Web forums
PDF document generation
Web services with XML and SOAP
Web 2.0 application with Ajax
You should be able to use any of these projects as is, or you can modify them to suit your needs. We chose them because we believe they represent some the most common web-based applications built by programmers. If your needs are different, this book should help you along the way to achieving your goals.
What Is PHP?
PHP is a server-side scripting language designed specifically for the Web. Within an HTML page, you can embed PHP code that will be executed each time the page is visited. Your PHP code is interpreted at the web server and generates HTML or other output that the visitor will see.
PHP was conceived in 1994 and was originally the work of one man, Rasmus Lerdorf. It was adopted by other talented people and has gone through four major rewrites to bring us the broad, mature product we see today. As of November 2007, it was installed on more than 21 million domains worldwide, and this number is growing rapidly. You can see the current number at http://www.php.net/usage.php.
PHP is an Open Source project, which means you have access to the source code and can use, alter, and redistribute it all without charge.
PHP originally stood for Personal Home Page but was changed in line with the GNU recursive naming convention (GNU = Gnu's Not Unix) and now stands for PHP Hypertext Preprocessor.
The current major version of PHP is 5. This version saw a complete rewrite of the underlying Zend engine and some major improvements to the language.
The home page for PHP is available at http://www.php.net.
The home page for Zend Technologies is http://www.zend.com.
What Is MySQL?
MySQL (pronounced My-Ess-Que-Ell) is a very fast, robust, relational database management system (RDBMS). A database enables you to efficiently store, search, sort, and retrieve data. The MySQL server controls access to your data to ensure that multiple users can work with it concurrently, to provide fast access to it, and to ensure that only authorized users can obtain access. Hence, MySQL is a multiuser, multithreaded server. It uses Structured Query Language (SQL), the standard database query language. MySQL has been publicly available since 1996 but has a development history going back to 1979. It is the world's most popular open source database and has won the Linux Journal Readers' Choice Award on a number of occasions.
MySQL is available under a dual licensing scheme. You can use it under an open source license (the GPL) free as long as you are willing to meet the terms of that license. If you want to distribute a non-GPL application including MySQL, you can buy a commercial license instead.
Why Use PHP and MySQL?
When setting out to build a website, you could use many different products.
You need to choose the following:
Hardware for the web server
An operating system
Web server software
A database management system
A programming or scripting language
Some of these choices are dependent on the others. For example, not all operating systems run on all hardware, not all web servers support all programming languages, and so on.
In this book, we do not pay much attention to hardware, operating systems, or web server software. We don't need to. One of the best features of both PHP and MySQL is that they work with any major operating system and many of the minor ones.
The majority of PHP code can be written to be portable between operating systems and web servers. There are some PHP functions that specifically relate to the filesystem that are operating system dependent, but these are clearly marked as such in the manual and in this book.
Whatever hardware, operating system, and web server you choose, we believe you should seriously consider using PHP and MySQL.
Some of PHP's Strengths
Some of PHP's main competitors are Perl, Microsoft ASP.NET, Ruby (on Rails or otherwise), JavaServer Pages (JSP), and ColdFusion.
In comparison to these products, PHP has many strengths, including the following:
Performance
Scalability
Interfaces to many different database systems
Built-in libraries for many common web tasks
Low cost
Ease of learning and use
Strong object-oriented support
Portability
Flexibility of development approach
Availability of source code
Availability of support and documentation
A more detailed discussion of these strengths follows.
Performance
PHP is very fast. Using a single inexpensive server, you can serve millions of hits per day. Benchmarks published by Zend Technologies (http://www.zend.com) show PHP outperforming its competition.
Scalability
PHP has what Rasmus Lerdorf frequently refers to as a "shared-nothing" architecture. This means that you can effectively and cheaply implement horizontal scaling with large numbers of commodity servers.
Database Integration
PHP has native connections available to many database systems. In addition to MySQL, you can directly connect to PostgreSQL, Oracle, dbm, FilePro, DB2, Hyperwave, Informix, InterBase, and Sybase databases, among others. PHP 5 also has a built-in SQL interface to a flat file, called SQLite.
Using the Open Database Connectivity Standard (ODBC), you can connect to any database that provides an ODBC driver. This includes Microsoft products and many others.
In addition to native libraries, PHP comes with a database access abstraction layer called PHP Database Objects (PDO), which allows consistent access and promotes secure coding practices.
Built-in Libraries
Because PHP was designed for use on the Web, it has many built-in functions for performing many useful web-related tasks. You can generate images on the fly, connect to web services and other network services, parse XML, send email, work with cookies, and generate PDF documents, all with just a few lines of code.
Cost
PHP is free. You can download the latest version at any time from http://www.php.net for no charge.
Ease of Learning PHP
The syntax of PHP is based on other programming languages, primarily C and Perl. If you already know C or Perl, or a C-like language such as C++ or Java, you will be productive using PHP almost immediately.
Object-Oriented Support
PHP version 5 has well-designed object-oriented features. If you learned to program in Java or C++, you will find the features (and generally the syntax) that you expect, such as inheritance, private and protected attributes and methods, abstract classes and methods, interfaces, constructors, and destructors. You will even find some less common features such as iterators. Some of this functionality was available in PHP versions 3 and 4, but the object-oriented support in version 5 is much more complete.
Portability
PHP is available for many different operating systems. You can write PHP code on free Unix-like operating systems such as Linux and FreeBSD, commercial Unix versions such as Solaris and IRIX, OS X, or on different versions of Microsoft Windows.
Well-written code will usually work without modification on a different system running PHP.
Flexibility of Development Approach
PHP allows you to implement simple tasks simply, and equally easily adapts to implementing large applications using a framework based on design patterns such as Model–View–Controller (MVC).
Source Code
You have access to PHP's source code. With PHP, unlike commercial, closed-source products, if you want to modify something or add to the language, you are free to do so.
You do not need to wait for the manufacturer to release patches. You also don't need to worry about the manufacturer going out of business or deciding to stop supporting a product.
Availability of Support and Documentation
Zend Technologies (http://www.zend.com), the company behind the engine that powers PHP, funds its PHP development by offering support and related software on a commercial basis.
The PHP documentation and community are mature and rich resources with a wealth of information to share.
What Is New in PHP 5?
You may have recently moved to PHP 5 from one of the PHP 4.x versions. As you would expect in a new major version, it has some significant changes. The Zend engine beneath PHP has been rewritten for this version. Major new features are as follows:
Better object-oriented support built around a completely new object model (see Chapter 6, "Object-Oriented PHP")
Exceptions for scalable, maintainable error handling (see Chapter 7, "Error and Exception Handling")
SimpleXML for easy handling of XML data (see Chapter 33, "Connecting to Web Services with XML and SOAP")
Other changes include moving some extensions out of the default PHP install and into the PECL library, improving streams support, and adding SQLite.
At the time of writing, PHP 5.2 was the current version, with PHP 5.3 on the near horizon. PHP 5.2 added a number of useful features including:
The new input filtering extension for security purposes
JSON extension for better JavaScript interoperability
File upload progress tracking
Better date and time handling
Many upgraded client libraries, performance improvements (including better memory management in the Zend Engine), and bug fixes
Key Features of PHP 5.3
You may have heard about a new major release of PHP, called PHP 6. At the time of this writing, PHP 6 is not in the release candidate stage, and hosting providers won't be installing it for mass use for quite some time. However, some of the key features planned in PHP 6 have been back-ported to PHP 5.3, which is a minor version release and closer to passing acceptance testing and thus installation by hosting providers (of course, if you are your own server's administrator, you can install any version you like).
Some of the new features in PHP 5.3 are listed below; additional information also appears throughout this book as appropriate:
The addition of namespaces; for more information see http://www.php.net/language.namespaces
The addition of the intl extension for application internationalization; for more information see http://www.php.net/manual/en/intro.intl.php
The addition of the phar extension for creating self-contained PHP application archives; for more information see http://www.php.net/book.phar
The addition of the fileinfo extension for enhanced ability to work with files; for more information see http://www.php.net/manual/en/book.fileinfo.php
The addition of the sqlite3 extension for working with the SQLite Embeddable SQL Database Engine; for more information see http://www.php.net/manual/en/class.sqlite3.php
The inclusion of support for the MySQLnd driver, a replacement for libmysql; for more information see http://forge.mysql.com/wiki/PHP_MYSQLND
While the list above contains some of the highly-touted features of PHP 5.3, the release also includes a significant number of bug fixes and maintenance performed on existing functionality, such as:
Removing support for any version of Windows older than Windows 2000 (such as Windows 98 and NT4)
Ensuring the PCRE, Reflection, and SPL extensions are always enabled
Adding a few date and time functions for ease of date calculation and manipulation
Improving the crypt(), hash(), and md5() functionality, as well as improving the OpenSSL extension
Improving php.ini administration and handling, including better error reporting
Continuing to fine-tune the Zend engine for better PHP runtime speed and memory usage
Some of MySQLs Strengths
MySQLs main competitors are PostgreSQL, Microsoft SQL Server, and Oracle.
MySQL has many strengths, including the following:
High performance
Low cost
Ease of configuration and learning
Portability
Availability of source code
Availability of support
A more detailed discussion of these strengths follows.
Performance
MySQL is undeniably fast. You can see the developers' benchmark page at http://web.mysql.com/whymysql/benchmarks. Many of these benchmarks show MySQL to be orders of magnitude faster than the competition. In 2002, eWeek published a benchmark comparing five databases powering a web application. The best result was a tie between MySQL and the much more expensive Oracle.
Low Cost
MySQL is available at no cost under an open source license or at low cost under a commercial license. You need a license if you want to redistribute MySQL as part of an application and do not want to license your application under an Open Source license. If you do not intend to distribute your application—typical for most web applications, or are working on free or open source Software, you do not need to buy a license.
Ease of Use
Most modern databases use SQL. If you have used another RDBMS, you should have no trouble adapting to this one. MySQL is also easier to set up than many similar products.
Portability
MySQL can be used on many different Unix systems as well as under Microsoft Windows.
Source Code
As with PHP, you can obtain and modify the source code for MySQL. This point is not important to most users most of the time, but it provides you with excellent peace of mind, ensuring future continuity and giving you options in an emergency.
Availability of Support
Not all open source products have a parent company offering support, training, consulting, and certification, but you can get all of these benefits from MySQL AB (http://www.mysql.com).
What Is New in MySQL 5?
Major changes introduced for MySQL 5 include
Views
Stored procedures (see Chapter 13, "Advanced MySQL Programming")
Basic trigger support
Cursor support
Other changes include more ANSI standard compliance and speed improvements.
If you are still using an early 4.x version or a 3.x version of the MySQL server, you should know that the following features were added to various versions from 4.0:
Subquery support
GIS types for storing geographical data
Improved support for internationalization
The transaction-safe storage engine InnoDB included as standard
The MySQL query cache, which greatly improves the speed of repetitive queries as often run by web applications
This book was written using MySQL 5.1 (Beta Community Edition). This version also added support for
Partitioning
Row based replication
Event scheduling
Logging to tables
Improvements to MySQL Cluster, information schema, backup processes, and many bug fixes
How Is This Book Organized?
This book is divided into five main parts:
Part I, "Using PHP," provides an overview of the main parts of the PHP language with examples. Each example is a real-world example used in building an e-commerce site rather than "toy" code. We kick off this section with Chapter 1, "PHP Crash Course." If you've already used PHP, you can whiz through this chapter. If you are new to PHP or new to programming, you might want to spend a little more time on it. Even if you are quite familiar with PHP but you are new to PHP 5, you will want to read Chapter 6, "Object-Oriented PHP," because the object-oriented functionality has changed significantly.
Part II, "Using MySQL," discusses the concepts and design involved in using relational database systems such as MySQL, using SQL, connecting your MySQL database to the world with PHP, and advanced MySQL topics, such as security and optimization.
Part III, "E-commerce and Security," covers some of the general issues involved in developing a website using any language. The most important of these issues is security. We then discuss how you can use PHP and MySQL to authenticate your users and securely gather, transmit, and store data.
Part IV, "Advanced PHP Techniques," offers detailed coverage of some of the major built-in functions in PHP. We have selected groups of functions that are likely to be useful when building a website. You will learn about interaction with the server, interaction with the network, image generation, date and time manipulation, and session variables.
Part V, "Building Practical PHP and MySQL Projects," is our favorite section. It deals with practical real-world issues such as managing large projects and debugging, and provides sample projects that demonstrate the power and versatility of PHP and MySQL.
Finally
We hope you enjoy this book and enjoy learning about PHP and MySQL as much as we did when we first began using these products. They are really a pleasure to use. Soon, you'll be able to join the many thousands of web developers who use these robust, powerful tools to easily build dynamic, real-time websites.
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