About the Authors Laura Thomson is a lecturer in the School of Computer Science and Information Technology at RMIT University in Melbourne, Australia. She is also a partner in the award-winning Web-development firm Tangled Web Design. Laura has previously worked for Telstra and the Boston Consulting Group. She holds a Bachelor of Applied Science (Computer Science) degree and a Bachelor of Engineering (Computer Systems Engineering) degree with honors, and is currently completing her Ph.D. in Adaptive Web Sites. In her spare time, she enjoys sleeping. Laura can be reached via email at laura@tangledweb.com.au. Luke Welling is a lecturer in the School of Computer Science and Information Technology at RMIT University in Melbourne, Australia. He is also a partner in Tangled Web Design. He holds a Bachelor of Applied Science (Computer Science) degree and is currently completing a master’s degree in Genetic Algorithms for Communication Network Design. In his spare time, he attempts to perfect his insomnia. Luke can be reached via email at luke@tangledweb.com.au. About the Contributors Israel Denis, Jr. is a freelance consultant working on e-commerce projects throughout the world. He specializes in integrating ERP packages such as SAP and Lawson with custom Web solutions.When he is not busy designing software or writing books, Israel enjoys traveling to Italy, a place he considers home. Israel obtained a master’s degree in Electrical Engineering from Georgia Tech in Atlanta, Georgia, in 1998. He is the author of numerous articles about Linux, Apache, PHP, and MySQL. He has worked for compa- nies such as GE and Procter & Gamble with mainly Unix-based computer systems. Israel can be reached via email at idenis@ureach.com. Chris Newman is a consultant programmer specializing in the development of dynam- ic Internet applications. He has extensive commercial experience using PHP and MySQL to produce a wide range of applications for an international client base.A grad- uate of Keele University, Chris lives in Stoke-on-Trent, England, where he runs Lightwood Consultancy Ltd., the company he founded in 1999 to further his interest in Internet development. Chris became fascinated with the potential of the Internet while at the university, and is thrilled to be working with cutting-edge technology. More infor- mation on Lightwood Consultancy Ltd. can be found at http://www.lightwood.net, and Chris can be contacted at chris@lightwood.net. Acknowledgments We would like to thank the team at Sams for all their hard work. In particular, we would like to thank Shelley Johnston without whose dedication and patience this book would not have been possible.We would also like to thank Israel Denis Jr. and Chris Newman for their valuable contributions. 00 525x fm 1/24/03 2:56 PM Page xxxi We appreciate immensely the work done by the PHP and MySQL development teams.Their work has made our lives easier for a number of years now, and continues to do so on a daily basis. We thank Adrian Close at eSec for saying “You can build that in PHP” back in 1998. He said we would like PHP, and it seems he was right. Finally, we would like to thank our family and friends for putting up with us while we have been antisocial for the better part of a year. Specifically, thank you for your sup- port to our family members: Julie, Robert, Martin, Lesley,Adam, Paul, James, Archer, and Barton. 00 525x fm 1/24/03 2:56 PM Page xxxii We Want to Hear from You! As the reader of this book, you are our most important critic and commentator.We value your opinion and want to know what we’re doing right, what we could do better, what areas you’d like to see us publish in, and any other words of wisdom you’re willing to pass our way. You can email or write me directly to let me know what you did or didn’t like about this book—as well as what we can do to make our books stronger. Please note that I cannot help you with technical problems related to the topic of this book, and that due to the high volume of mail I receive, I might not be able to reply to every message. When you write, please be sure to include this book’s title and author as well as your name and phone or email address. I will carefully review your comments and share them with the author and editors who worked on the book. Email: opensource@samspublishing.com Mail: Mark Taber Associate Publisher Sams Publishing 201 West 103rd Street Indianapolis, IN 46290 USA Reader Services For more information about this book or others from Sams Publishing, visit our Web site at www.samspublishing.com.Type the ISBN (excluding hyphens) or the title of the book in the Search box to find the book you’re looking for. For a list of known errors and any updates to the book’s source code please check www.lukelaura.com. 00 525x fm 1/24/03 2:56 PM Page xxxiii 00 525x fm 1/24/03 2:56 PM Page xxxiv Introduction WELCOME TO PHP AND MYSQL W EB 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’ll cover n Why you should read this book n What you will be able to achieve using this book n What PHP and MySQL are and why they’re great n An overview of the latest features of PHP 4 n How this book is organized Let’s get started. Why You Should Read This Book This book will teach you how to create interactive Web sites from the simplest order form to complex secure e-commerce 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 begin- ning programmer, you should still find this book useful, but it might take you a little longer to digest.We’ve tried not to leave out any basic concepts, but we do cover them at speed.The typical reader of this book is someone who wants to master PHP and MySQL for the purpose of building a large or commercial Web site.You might already be working in another Web development language; if so, this book should get you up to speed quickly. We wrote this book because we were tired of finding books on PHP that were basi- cally a function reference.These books are useful, but they don’t help when your boss or client has said “Go build me a shopping cart.”We have done our best to make every example useful. Many of the code samples can be directly used in your Web site, and many others can be used with minor modifications. 01 525x intro 1/24/03 3:39 PM Page 1 . xxxiv Introduction WELCOME TO PHP AND MYSQL W EB 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. author of numerous articles about Linux, Apache, PHP, and MySQL. He has worked for compa- nies such as GE and Procter & Gamble with mainly Unix-based computer systems. Israel can be reached. the development of dynam- ic Internet applications. He has extensive commercial experience using PHP and MySQL to produce a wide range of applications for an international client base.A grad- uate