What Is PHP?

What Is PHP?
PHP is an open-source, server-side, HTML-embedded Web-scripting language that is compati- ble with all the major Web servers (most notably Apache). PHP enables you to embed code fragments in normal HTML pages—code that is interpreted as your pages are served up to users. PHP also serves as a “glue” language, making it easy to connect your Web pages to server-side databases.
Why PHP ?
We devote nearly all of Chapter 1 to this question. The short answer is that it’s free, it’s open
source, it’s full featured, it’s cross-platform, it’s stable, it’s fast, it’s clearly designed, it’s easy
to learn, and it plays well with others.
What’s New in This Edition?
Although this book has a new title, it is in some sense a third edition. Previous versions were:
✦ PHP 4 Bible. Published in August 2000, covering PHP through version 4.0.
✦ PHP Bible, Second Edition. Published in September 2002, a significantly expanded ver-
sion of the first edition, current through PHP 4.2.
Our initial plan for this book was to simply reorganize the second edition and bring it up
to date with PHP5. We realized, however, that although the previous editions covered
PHP/MySQL interaction, we had left readers in the dark about how to create and administer
MySQL databases in the first place, and this led to many reader questions. As a result, we
decided to beef up the coverage of MySQL and change the title.
New PHP5 features
Although much of PHP4’s functionality survives unchanged in PHP5, there have been some
deep changes. Among the ones we cover are:
✦ Zend Engine 2 and the new object model, with support for private/protected members,
abstract classes, and interfaces

✦ PHP5’s completely reworked XML support, built around libmxl2

✦ Exceptions and exception handling

MySQL coverage
We now cover MySQL 4.0 installation, database design, and administration, including back-
ups, replication, and recovery. As with previous editions, we devote much of the book to
techniques for writing MySQL-backed PHP applications.
Other new material
In addition to MySQL- and PHP5-specific features, we’ve added:
✦ Improved coverage of databases other than MySQL (Oracle, PostgreSQL, and the PEAR
database interaction layer)

✦ The PEAR code repository

✦ A chapter on integrating PHP and Java

✦ Separate chapters on error-handling and debugging techniques

Finally, we reorganized the entire book, pushing more advanced topics toward the end, to
give beginners an easier ramp up.
Who wrote the book?
The first two editions were by Converse and Park, with a guest chapter by Dustin Mitchell
and tech editing by Richard Lynch. For this version, Clark Morgan took on much of the revi-
sion work, with help by Converse and Park as well as by David Wall and Chris Cornell, who
also contributed chapters and did technical editing.
Whom This Book Is For
This book is for anyone who wants to build Web sites that exhibit more complex behavior
than is possible with static HTML pages. Within that population, we had the following three

particular audiences in mind:

✦ Web site designers who know HTML and want to move into creating dynamic Web sites
✦ Experienced programmers (in C, Java, Perl, and so on) without Web experience who
want to quickly get up to speed in server-side Web programming
✦ Web programmers who have used other server-side technologies (Active Server Pages,
Java Server Pages, or ColdFusion, for example) and want to upgrade or simply add
another tool to their kit. We assume that the reader is familiar with HTML and has a basic knowledge of the workings of the Web, but we do not assume any programming experience beyond that. To help save time for more experienced programmers, we include a number of notes and asides that com- pare PHP with other languages and indicate which chapters and sections may be safely skipped. Finally, see our appendixes, which offer specific advice for C programmers, ASP coders, and pure-HTML designers.