PHP and MySQL For Dummies E-Book

Janet Valade

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 604

Veröffentlichungsjahr: 2009

Beschreibung

Here's what Web designers need to know to create dynamic, database-driven Web sites To be on the cutting edge, Web sites need to serve up HTML, CSS, and products specific to the needs of different customers using different browsers. An effective e-commerce site gathers information about users and provides information they need to get the desired result. PHP scripting language with a MySQL back-end database offers an effective way to design sites that meet these requirements. This full updated 4th Edition of PHP & MySQL For Dummies gets you quickly up to speed, even if your experience is limited. * Explains the easy way to install and set up PHP and MySQL using XAMPP, so it works the same on Linux, Mac, and Windows * Shows you how to secure files on a Web host and how to write secure code * Packed with useful and understandable code examples for Web site creators who are not professional programmers * Fully updated to ensure your code will be compliant based on PHP 5.3 and MySQL 5.1.31 * Provides clear, accurate code examples PHP & MySQL For Dummies, 4th Edition provides what you need to know to create sites that get results. Note: CD-ROM/DVD and other supplementary materials are not included as part of eBook file.

Leseprobe

PHP & MySQL® For Dummies®

Table of Contents

Introduction

About This Book

Conventions Used in This Book

What You’re Not To Read

Foolish Assumptions

How This Book Is Organized

Part I: Developing a Web Database Application Using PHP and MySQL

Part II: MySQL Database

Part III: PHP

Part IV: Applications

Part V: The Part of Tens

Part VI: Appendixes

Icons Used in This Book

Where to Go from Here

Part I: Developing a Web Database Application Using PHP and MySQL

Chapter 1: Introduction to PHP and MySQL

What Is a Web Database Application?

The database: Storing data

The application: Moving data in and out of the database

MySQL, My Database

Advantages of MySQL

How MySQL works

Communicating with the MySQL server

PHP, a Data Mover

Advantages of PHP

How PHP works

MySQL and PHP, the Perfect Pair

Advantages of the relationship

How MySQL and PHP work together

Keeping Up with PHP and MySQL Changes

PHP versions

MySQL versions

Chapter 2: Setting Up Your Work Environment

Anatomy of a Web Site

Building a Web Site

Deciding Where to Publish Your Web Site

Using a Web hosting company

Using a company Web site

Setting up your own server

Deciding Where to Develop Your Web Site

On your own computer

On another computer

Setting Up Your Web Site

With a Web hosting company

On a company Web site

Information you need

Setting Up Your Development Environment

Your own computer

Web hosting company

A company computer

Testing, Testing, 1,2,3

Understanding PHP/MySQL functions

Testing PHP

Testing your local PHP configuration file

Testing MySQL

Chapter 3: Developing a Web Database Application

Planning Your Web Database Application

Identifying what you want from the application

Taking the user into consideration

Making the site easy to use

Leaving room for expansion

Writing it down

Presenting the Two Running Examples in This Book

Stuff for Sale

Members Only

Designing the Database

Choosing the data

Organizing the data

Designing the Sample Databases

Pet Catalog design process

Members Only design process

Types of Data

Character data

Numerical data

Date and time data

Enumeration data

MySQL data type names

Writing it down

Taking a Look at the Sample Database Designs

Stuff for Sale database tables

Members Only database tables

Developing the Application

Building the database

Writing the programs

Part II: MySQL Database

Chapter 4: Building the Database

Communicating with MySQL

Building SQL queries

Sending SQL queries

Building a Database

Creating a new database

Viewing the databases

Deleting a database

Adding tables to a database

Changing the database structure

Moving Data Into and Out of the Database

Adding information

Viewing information

Retrieving information

Combining information from tables

Updating information

Removing information

Chapter 5: Protecting Your Data

Controlling Access to Your Data

Understanding account names and hostnames

Finding out about passwords

Taking a look at account privileges

Setting Up MySQL Accounts

Adding accounts

Allowing access to a database

Changing privileges

Adding and changing passwords

Removing accounts

Backing Up Your Data

Exporting your data with phpMyAdmin

Viewing the Export file

Restoring Your Data

Part III: PHP

Chapter 6: General PHP

Adding a PHP Section to an HTML Page

Writing PHP Statements

Using PHP Variables

Naming a variable

Creating and assigning values to variables

Dealing with notices

Using PHP Constants

Working with Numbers

Working with Character Strings

Single-quoted strings versus double-quoted strings

Joining strings

Working with Dates and Times

Setting local time

Formatting a date

Storing a timestamp in a variable

Using dates with MySQL

Comparing Values

Making simple comparisons

Matching character strings to patterns

Joining Comparisons with and/or/xor

Adding Comments to Your Program

Chapter 7: PHP Building Blocks for Programs

Useful Simple Statements

Using echo statements

Using assignment statements

Using increment statements

Using exit

Using function calls

Using PHP Arrays

Creating arrays

Viewing arrays

Removing values from arrays

Sorting arrays

Getting values from arrays

Walking through an array

Multidimensional arrays

Useful Conditional Statements

Using if statements

Using switch statements

Using Loops

Using for loops

Using while loops

Using do..while loops

Infinite loops

Breaking out of a loop

Using Functions

Using variables in functions

Passing values between a function and the main program

Using built-in functions

Chapter 8: Data In, Data Out

PHP and MySQL Functions

Making a Connection

Connecting to the MySQL server

Selecting the right database

Sending SQL queries

Getting Information from a Database

Sending a SELECT query

Getting and using the data

Using functions to get data

Getting Information from the User

Using HTML forms

Making forms dynamic

Using the information from the form

Checking the information

Giving users a choice with multiple submit buttons

Putting Information into a Database

Preparing the data

Adding new information

Updating existing information

Getting Information in Files

Using a form to upload the file

Processing the uploaded file

Putting it all together

Chapter 9: Moving Information from One Web Page to the Next

Moving Your User from One Page to Another

Moving Information from Page to Page

Adding information to the URL

Storing information via cookies

Passing information with HTML forms

Using PHP Sessions

Understanding how PHP sessions work

Opening sessions

Using PHP session variables

Sessions without cookies

Making sessions private

Closing PHP sessions

Part IV: Applications

Chapter 10: Putting It All Together

Organizing the Application

Organizing at the application level

Organizing at the program level

Keeping It Private

Ensure the security of the computer

Don’t let the Web server display filenames

Hide things

Don’t trust information from users

Use a secure Web server

Completing Your Documentation

Chapter 11: Building an Online Catalog

Designing the Application

Showing pets to the customers

Adding pets to the catalog

Building the Database

Building the Pet table

Building the PetType table

Building the Color table

Adding data to the database

Designing the Look and Feel

Showing pets to the customers

Adding pets to the catalog

Writing the Programs

Showing pets to the customers

Adding pets to the catalog

Chapter 12: Building a Members Only Web Site

Designing the Application

Building the Database

Building the Member table

Building the Login table

Adding data to the database

Designing the Look and Feel

Storefront page

Login page

New Member Welcome page

Members Only section

Writing the Programs

Writing PetShopFront

Writing Login

Writing New_member

Writing the Members Only section

Planning for Growth

Part V: The Part of Tens

Chapter 13: Ten Things You Might Want to Do Using PHP Functions

Communicate with MySQL

Send E-Mail

Use PHP Sessions

Stop Your Program

Handle Arrays

Check for Variables

Format Values

Compare Strings to Patterns

Find Out about Strings

Change the Case of Strings

Chapter 14: Ten PHP Gotchas

Missing Semicolons

Not Enough Equal Signs

Misspelled Variable Names

Missing Dollar Signs

Troubling Quotes

Invisible Output

Numbered Arrays

Including PHP Statements

Missing Mates

Confusing Parentheses and Brackets

Part VI: Appendixes

Appendix A: Installing PHP, MySQL, and Apache from XAMPP

Appendix B: Configuring PHP

In the general php.ini file

In a php.ini file on your Web site

PHP & MySQL® For Dummies®

by Janet Valade

PHP & MySQL® For Dummies®, 4th Edition

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About the Author

Janet Valade is the author of PHP & MySQL Web Development All-in-One Desk Reference For Dummies, PHP 5 For Dummies, PHP & MySQL Everyday Apps For Dummies, and PHP & MySQL: Your visual blueprint for creating dynamic, database-driven Web sites, as well as the first, second, and third editions of this book. In addition, Janet is the author of Spring into Linux and a coauthor of Mastering Visually Dreamweaver 8 and Flash 8.

Janet has twenty years of experience in the computing field. Most recently, she worked as a Web designer and programmer in an engineering firm for four years. Before that, Janet worked for thirteen years in a university environment, where she was a systems analyst. During her tenure, she supervised the installation and operation of computing resources, designed and developed a data archive, supported faculty and students in their computer usage, wrote numerous technical papers, and developed and presented seminars on a variety of technology topics.

To keep in touch, see janetvalade.com.

Author’s Acknowledgments

First, I want to express my appreciation to the entire open source community. Without those who give their time and talent, there would be no cool PHP and MySQL for me to write about. Furthermore, I never would have learned this software without the lists, where people generously spend their time answering foolish questions from beginners.

I want to thank my mother for passing on a writing gene, along with many other things. And my children always for everything. My thanks to my friends Art, Dick, and Marge for responding to my last-minute call for help. I particularly want to thank Sammy, Dude, Spike, Lucky, Upanishad, Sadie, and E.B. for their important contributions.

And, of course, I want to thank the professionals who make it all possible. Without the people at Wiley, this book would not exist. Because they all do their jobs so well, I can contribute my part to this joint project.

Publisher’s Acknowledgments

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Introduction

Welcome to the exciting world of Web database applications. This book provides the basic techniques to build any Web database application, but I certainly recommend that you start with a simple one. In this book, I develop two sample applications, both chosen to represent two types of applications frequently encountered on the Web: product catalogs and customer- or member-only sites that require the user to register and log in with a password. The sample applications are complicated enough to require more than one program and to use a variety of data and data manipulation techniques, yet simple enough to be easily understood and adapted to a variety of Web sites. After you master the simple applications, you can expand the basic design to include all the functionality that you can think of.

About This Book

Think of this book as your friendly guide to building a Web database application. This book is designed as a reference, not as a tutorial, so you don’t have to read it from cover to cover. You can start reading at any point — in Chapter 1, Chapter 9, wherever. I divide the task of building a Web database application into manageable chunks of information, so check out the table of contents and locate the topic that you’re interested in. If you need to know information from another chapter to understand the chapter you’re reading, I reference that chapter.

Here’s a sample of the topics I discuss:

Building and using a MySQL database

Adding PHP to HTML files

Using the features of the PHP language

Using HTML forms to collect information from users

Showing information from a database in a Web page

Storing information in a database

Conventions Used in This Book

This book includes many examples of PHP programming statements, MySQL statements, and HTML. Such statements are shown in a different typeface, which looks like the following line:

A PHP program statement

In addition, snippets or key terms of PHP, MySQL, and HTML are sometimes shown in the text of a paragraph. When they are, the special text in the paragraph is also shown in the example typeface, different than the paragraph typeface. For instance, this text is an example of a PHP statement within the paragraph text.

In examples, you will often see some words in italic. Italicized words are general types that need to be replaced with the specific name appropriate for your data. For instance, when you see an example like the following:

SELECT field1,field2 FROM tablename

field1,field2, and tablename need to be replaced with real names because they are in italic. When you use this statement in your program, you might use it in the following form:

SELECT name,age FROM Customer

In addition, you might see three dots (...) following a list in an example line. You don’t type the three dots. They just mean that you can have as many items in the list as you want. For instance, when you see

SELECT field1,field2,... FROM tablename

the three dots just mean that your list of fields can be longer than two. It means you can go on with field3, field4, and so forth. For example, your statement might be

SELECT name,age,height,shoesize FROM Customer

From time to time, you’ll also see something in bold. Pay attention to these; they indicate something I want you to see or something you need to type.

What You’re Not To Read

Some information in this book is flagged as Technical Stuff with an icon off to the left. Sometimes you’ll see this technical stuff in a sidebar: Consider it information that you don’t need to read to create a Web database application. This extra information might contain a further look under the hood or describe a technique that requires more technical knowledge to execute. Some readers may be interested in the extra technical information or techniques, but feel free to ignore them if you don’t find them interesting or useful.

Foolish Assumptions

To write a focused book rather than an encyclopedia, I needed to assume some background for you, the reader. I assumed that you know HTML and CSS and have created Web sites with HTML and CSS. Consequently, although I use HTML/CSS in many examples, I do not explain the HTML/CSS. If you don’t have an HTML background, this book will be more difficult to use. I suggest that you read an HTML book — such as HTML, XHTML & CSS For Dummies by Ed Tittel and Jeff Noble (Wiley) — and build some practice Web pages before you start this book. In particular, some background in HTML forms and tables is useful. However, if you’re the impatient type, I won’t tell you it’s impossible to proceed without knowing HTML and CSS. You may be able to glean enough HTML and CSS from this book to build your particular Web site. If you choose to proceed without knowing HTML, I suggest that you have an HTML book by your side to assist you.

If you’re proceeding without any experience with Web pages, you might not know some required basics. You must know how to create and save plain text files with an editor such as Notepad or save the file as plain text from your word processor (not in the word processor format). You also must know where to put the text files containing the code (HTML or PHP) for your Web pages so that the pages are available to all users with access to your Web site, and you must know how to move the files to the appropriate location.

You do not need to know how to design or create databases or how to program. All the information that you need to know about databases and programming is included in this book.

How This Book Is Organized

This book is divided into six parts, with several chapters in each part. The content ranges from an introduction to PHP and MySQL to installing to creating and using databases to writing PHP programs.

Part I: Developing a Web Database Application Using PHP and MySQL

Part I provides an overview of using PHP and MySQL to create a Web database application. It describes and gives the advantages of PHP, of MySQL, and of their use together. You find out how to get started, including what you need, how to get access to PHP and MySQL, and how to test your software. You then find out about the process of developing the application.

Part II: MySQL Database

In Part II you find out the details of working with MySQL databases. You create a database, change a database, and move data into and out of a database.

Part III: PHP

Part III provides the details of writing PHP programs that enable your Web pages to insert new information, update existing information, or remove information from a MySQL database. You find out how to use the PHP features that are used for database interaction and forms processing.

Part IV: Applications

Part IV describes the Web database application as a whole. You find out how to organize the PHP programs into a functioning application that interacts with the database. Two complete sample applications are provided, described, and explained.

Part V: The Part of Tens

Part V provides some useful lists of important things to do and not to do when developing a Web database application.

Part VI: Appendixes

The final part, Part VI, provides instructions for installing PHP and MySQL for those who need to install the software themselves. Appendix B discusses how to configure PHP.

Icons Used in This Book

This icon is a sticky note of sorts, highlighting information that’s worth committing to memory.

This icon flags information and techniques that are more technical than other sections of the book. The information here can be interesting and helpful, but you don’t need to understand it to use the information in the book.

Tips provide extra information for a specific purpose. Tips can save you time and effort, so they’re worth checking out.

You should always read warnings. Warnings emphasize actions that you must take or must avoid to prevent dire consequences.

Where to Go from Here

This book is organized in the order in which things need to be done. If you’re a newbie, you probably need to start with Part I, which describes how to get started, including how to design the pieces of your application and how the pieces will interact. When implementing your application, you need to create the MySQL database first, so I discuss MySQL before PHP. After you understand the details of MySQL and PHP, you need to put them together into a complete application, which I describe in Part IV. If you’re already familiar with any part of the book, you can go directly to the part that you need. For instance, if you’re familiar with database design, you can go directly to Part II, which describes how to implement the design in MySQL. Or if you know MySQL, you can just read about PHP in Part III.

And if you want even more information, check out the cheat sheet at www.dummies.com/cheatsheet/phpmysql.

Part I

Developing a Web Database Application Using PHP and MySQL

In this part . . .

In this part, I provide an overview. I describe PHP and MySQL, how each one works, and how they work together to make your Web database application possible. After describing your tools, I show you how to set up your working environment. I present your options for accessing PHP and MySQL and point out what to look for in each environment.

After describing your tools and your options for your development environment, I provide an overview of the development process. I discuss planning, design, and building your application.

Chapter 1

Introduction to PHP and MySQL

In This Chapter

Finding out what a Web database application is

Discovering how MySQL works

Taking a look at PHP

Finding out how PHP and MySQL work together

So you need to develop an interactive Web site. Perhaps your boss just put you in charge of the company’s online product catalog. Or you want to develop your own Web business. Or your sister wants to sell her paintings online. Or you volunteered to put up a Web site open only to members of your circus acrobats’ association. Whatever your motivation might be, you can see that the application needs to store information (such as information about products or member passwords), thus requiring a database. You can see also that the application needs to interact dynamically with the user; for instance, the user selects a product to view or enters membership information. This type of Web site is a Web database application.

I assume that you’ve created static Web pages before, using HTML (HyperText Markup Language), but creating an interactive Web site is a new challenge, as is designing a database. You asked three computer gurus you know what you should do. They said a lot of things you didn’t understand, but among the technical jargon, you heard “quick” and “easy,” and “free” mentioned in the same sentence as PHP and MySQL. Now you want to know more about using PHP and MySQL to develop the Web site that you need.

PHP and MySQL work together very well; it’s a dynamic partnership. In this chapter, you find out the advantages of each, how each one works, and how they work together to produce a dynamic Web database application.

What Is a Web Database Application?

An application is a program or a group of programs designed for use by an end user (for example, customers, members, or circus acrobats). If the end user interacts with the application via a Web browser, the application is a Web based or Web application. If the Web application requires the long-term storage of information using a database, it’s a Web database application. This book provides you with the information that you need to develop a Web database application that can be accessed with Web browsers such as Internet Explorer and Firefox.

A Web database application is designed to help a user accomplish a task. It can be a simple application that displays information in a browser window (for example, current job openings when the user selects a job title) or a complicated program with extended functionality (for example, the book-ordering application at Amazon.com or the bidding application at eBay).

A Web database application consists of just two pieces:

Database: The database is the long-term memory of your Web database application. The application can’t fulfill its purpose without the database. However, the database alone is not enough.

Application: The application piece is the program or group of programs that performs the tasks. Programs create the display that the user sees in the browser window; they make your application interactive by accepting and processing information that the user types in the browser window; and they store information in the database and get information out of the database. (The database is useless unless you can move data in and out.)

The Web pages that you’ve previously created with HTML alone are static, meaning the user can’t interact with the Web page. All users see the same Web page. Dynamic Web pages, on the other hand, allow the user to interact with the Web page. Different users might see different Web pages. For instance, one user looking at a furniture store’s online product catalog might choose to view information about the sofas, whereas another user might choose to view information about coffee tables. To create dynamic Web pages, you must use another language in addition to HTML.

One language widely used to make Web pages dynamic is JavaScript. JavaScript is useful for several purposes, such as mouse-overs (for example, to highlight a navigation button when the user moves the mouse pointer over it) or accepting and validating information that users type into a Web form. However, it’s not useful for interacting with a database. You wouldn’t use JavaScript to move the information from the Web form into a database. PHP, however, is a language particularly well suited to interacting with databases. PHP can accept and validate the information that users type into a Web form and can also move the information into a database. The programs in this book are written with PHP.

The database: Storing data

The core of a Web database application is the database, which is the long-term memory (I hope more efficient than my long-term memory) that stores information for the application. A database is an electronic file cabinet that stores information in an organized manner so that you can find it when you need it. After all, storing information is pointless if you can’t find it. A database can be small, with a simple structure — for example, a database containing the titles and authors’ names of all the books that you own. Or a database can be huge, with an extremely complex structure — such as the database that Amazon.com has to hold all its information.

The information that you store in the database comes in many varieties. A company’s online catalog requires a database to store information about all the company’s products. A membership Web site requires a database to store information about members. An employment Web site requires a database (or perhaps two databases) to store information about job openings and information from résumés. The information that you plan to store could be similar to information that’s stored by Web sites all over the Internet — or information that’s unique to your application.

The term database refers to the file or group of files that holds the actual data. The data is accessed by using a set of programs called a DBMS (Database Management System). Almost all DBMSs these days are RDBMSs (Relational Database Management Systems), in which data is organized and stored in a set of related tables.

In this book, MySQL is the RDBMS used because it’s particularly well suited for Web sites. MySQL and its advantages are discussed in the section, “MySQL, My Database,” later in this chapter. You can find out how to organize and design a MySQL database in Chapter 3.

The application: Moving data in and out of the database

For a database to be useful, you need to be able to move data into and out of it. Programs are your tools for this because they interact with the database to store and retrieve data. A program connects to the database and makes a request: “Take this data and store it in the specified location.” Another program makes the request: “Find the specified data and give it to me.” The application programs that interact with the database run when the user interacts with the Web page. For instance, when the user clicks the submit button after filling in a Web form, a program processes the information in the form and stores it in a database.

E-mail discussion lists

Good technical support is available from e-mail discussion lists, which are groups of people discussing specific topics through e-mail. E-mail lists are available for pretty much any subject you can think of: Powerball, ancient philosophy, cooking, The Beatles, Scottish terriers, politics, and so on. The list manager maintains a distribution list of e-mail addresses for anyone who wants to join the discussion. When you send a message to the discussion list, your message is sent to the entire list so that everyone can see it. Thus, the discussion is a group effort, and anyone can respond to any message that interests him or her.

E-mail discussion lists are supported by various sponsors. Any individual or organization can run a list. Most software vendors run one or more lists devoted to their software. Universities run many lists for educational subjects. In addition, some Web sites manage discussion lists, such as Yahoo! Groups and Topica. Users can create a new list or join an existing list through the Web application.

Software-related e-mail lists are a treasure trove of technical support. Anywhere from a hundred to several thousand users of the software subscribe to the list. Often the developers, programmers, and technical support staff for the software vendor are on the list. You’re unlikely to be the first person to ever experience your problem. Whatever your question or problem, someone on the list probably knows the answer or the solution. When you post a question to an e-mail list, the answer usually appears in your inbox within minutes. In addition, most lists maintain an archive of previous discussions so that you can search for answers. When you’re new to any software, you can find out a great deal simply by joining the discussion list and reading the messages for a few days.

PHP and MySQL have e-mail discussion lists. Actually, each has several discussion lists for special topics, such as databases and PHP. You can find the names of the mailing lists and instructions for joining them on the PHP (www.php.net) and MySQL (www.mysql.com) Web sites.

MySQL, My Database

MySQL is a fast, easy-to-use RDBMS used on many Web sites. Speed was the developers’ main focus from the beginning. In the interest of speed, they made the decision to offer fewer features than their major competitors (such as Oracle and Sybase). However, even though MySQL is less full-featured than its commercial competitors, it has all the features needed by the majority of database developers. It’s easier to install and use than its commercial competitors, and the difference in price is strongly in favor of MySQL.

MySQL was developed originally by a Swedish company but is now developed, marketed, and supported by Sun Microsystems. The company licenses it in two ways:

MySQL Community Server: A freely downloadable, open source edition of MySQL, released early and often with the most advanced features. Anyone who can meet the requirements of the GPL can use the software for free. If you’re using MySQL as a database on a Web site (the subject of this book), you can use MySQL for free, even if you’re making money with your Web site.

MySQL Enterprise Subscription: A comprehensive offering of production support, monitoring tools, and MySQL database software. For a subscription fee paid per year per server, monthly software updates, consulting services, technical support, and other services are available. You can choose the level of services you want for the fee that you want to pay.

Finding technical support for MySQL Community Server is not a problem. You can join one of several e-mail discussion lists offered on the MySQL Web site at www.mysql.com. You can even search the e-mail list archives, which contain a large archive of MySQL questions and answers.

Advantages of MySQL

MySQL is a popular database with Web developers. Its speed and small size make it ideal for a Web site. Add to that the fact that it’s open source, which means free, and you have the foundation of its popularity. Here’s a rundown of some of its advantages:

It’s fast. The main goal of the folks who developed MySQL was speed. Thus, the software was designed from the beginning with speed in mind.

It’s inexpensive. MySQL is free under the open source GPL license, and the fee for a commercial license is reasonable.

It’s easy to use. You can build and interact with a MySQL database by using a few simple statements in the SQL language, which is the standard language for communicating with RDBMSs. Check out Chapter 4 for the lowdown on the SQL language.

It can run on many operating systems. MySQL runs on many operating systems — Windows, Linux, Mac OS, most varieties of Unix (including Solaris and AIX), FreeBSD, OS/2, Irix, and others.

It’s available on almost all Web hosts. If you’re going to run your Web site on a Web hosting company, MySQL is widely available without extra cost. Using MySQL on a Web host is discussed in more detail in Chapter 2.

Technical support is widely available. A large base of users provides free support through mailing lists. The MySQL developers also participate in the e-mail lists.

It’s secure. MySQL’s flexible system of authorization allows some or all database privileges (such as the privilege to create a database or delete data) to specific users or groups of users. Passwords are encrypted.

It supports large databases. MySQL handles databases up to 50 million rows or more. The default file size limit for a table is 4GB, but you can increase this (if your operating system can handle it) to a theoretical limit of 8 million terabytes (TB).

It’s customizable. The open source GPL license allows programmers to modify the MySQL software to fit their own specific environments.

How MySQL works

The MySQL software consists of the MySQL server, several utility programs that assist in the administration of MySQL databases, and some supporting software that the MySQL server needs (but you don’t need to know about). The heart of the system is the MySQL server.

The MySQL server is the manager of the database system. It handles all your database instructions. For instance, if you want to create a new database, you send a message to the MySQL server that says “create a new database and call it newdata.” The MySQL server then creates a subdirectory in its data directory, names the new subdirectory newdata,and puts the necessary files with the required format into the newdata subdirectory. In the same manner, to add data to that database, you send a message to the MySQL server, giving it the data and telling it where you want the data to be added. You find out how to write and send messages to MySQL in Part II.

Before you can pass instructions to the MySQL server, it must be running and waiting for requests. The MySQL server is usually set up so that it starts when the computer starts and continues running all the time. This is the usual setup for a Web site. However, it’s not necessary to set it up to start when the computer starts. If you need to, you can start it manually whenever you want to access a database. When it’s running, the MySQL server listens continuously for messages that are directed to it.

Communicating with the MySQL server

All your interaction with the database is accomplished by passing messages to the MySQL server. You can send messages to the MySQL server several ways, but this book focuses on sending messages using PHP. The PHP software has specific statements that you use to send instructions to the MySQL server.

The MySQL server must be able to understand the instructions that you send it. You communicate by using SQL (Structured Query Language), which is a standard language understood by many RDBMSs. The MySQL server understands SQL. PHP doesn’t understand SQL, but it doesn’t need to: PHP just establishes a connection with the MySQL server and sends the SQL message over the connection. The MySQL server interprets the SQL message and follows the instructions. The MySQL server sends a return message, stating its status and what it did (or reporting an error if it was unable to understand or follow the instructions).

Software designed specifically to interact with MySQL database is also discussed in this book. You can use this software, called phpMyAdmin, on your own computer to communicate with your MySQL databases. PhpMyAdmin is also available on almost all Web hosts.

For the lowdown on how to write and send SQL messages to MySQL, check out Part II.

PHP, a Data Mover

PHP, a scripting language designed specifically for use on the Web, is your tool for creating dynamic Web pages. Rich in features that make Web design and programming easier, PHP is in use on more than 20 million domains (according to the Netcraft survey at www.php.net/usage.php). Its popularity continues to grow, so it must be fulfilling its function pretty well.

PHP stands for PHP: HyperText Preprocessor. In its early development by a guy named Rasmus Lerdorf, it was called Personal Home Page tools. When it developed into a full-blown language, the name was changed to be more in line with its expanded functionality.

The syntax of the PHP language is similar to the syntax of C, so if you have experience with C, you’ll be comfortable with PHP. PHP is actually simpler than C because it doesn’t use some of the more difficult concepts of C. PHP also doesn’t include the low-level programming capabilities of C because PHP is designed to program Web sites and doesn’t require the capabilities required by C.

PHP is particularly strong in its ability to interact with databases. It supports pretty much every database you’ve ever heard of (and some you haven’t). PHP handles connecting to the database and communicating with it. You don’t need to know the technical details for connecting to a database or for exchanging messages with it. You tell PHP the name of the database and where it is, and PHP handles the details. It connects to the database, passes your instructions to the database, and returns the database response to you.

Technical support is available for PHP. You can join one of several e-mail discussion lists offered on the PHP Web site (www.php.net), including a list for databases and PHP. In addition, a Web interface to the discussion lists is available at http://news.php.net, where you can browse or search the messages.

Advantages of PHP

The popularity of PHP is growing rapidly because of its many advantages:

It’s fast. Because it is embedded in HTML code, the response time is short.

It’s inexpensive — free, in fact. PHP is proof that free lunches do exist and that you can get more than you paid for.

It’s easy to use. PHP contains many special features and functions needed to create dynamic Web pages. The PHP language is designed to be included easily in an HTML file.

It can run on many operating systems. It runs on a variety of operating systems — Windows, Linux, Mac OS, and most varieties of Unix.

It’s available on almost all Web hosts. If you are going to publish your Web site on a Web host, you will find PHP installed on almost all Web hosts for free.

Technical support is widely available. A large base of users provides free support through e-mail discussion lists.

It’s secure. The user does not see the PHP code.

It’s designed to support databases. PHP includes functionality designed to interact with specific databases. It relieves you of the need to know the technical details required to communicate with a database.

It’s customizable. The open source license allows programmers to modify the PHP software, adding or modifying features as needed to fit their own specific environments.

How PHP works

PHP is an embedded scripting language when used in Web pages. This means that PHP code is embedded in HTML code. You use HTML tags to enclose the PHP language that you embed in your HTML file — the same way that you would use other HTML tags. You create and edit Web pages containing PHP the same way that you create and edit regular HTML pages.

The PHP software works with the Web server. The Web server is the software that delivers Web pages to the world. When you type a URL into your Web browser, you’re sending a message to the Web server at that URL, asking it to send you an HTML file. The Web server responds by sending the requested file. Your browser reads the HTML file and displays the Web page. You also request the Web server to send you a file when you click a link in a Web page. In addition, the Web server processes a file when you click a Web page button that submits a form.

When PHP is installed, the Web server is configured to expect certain file extensions to contain PHP language statements. Often the extension is .php or .phtml, but any extension can be used. When the Web server gets a request for a file with the designated extension, it sends the HTML statements as is, but PHP statements are processed by the PHP software before they’re sent to the requester.

When PHP language statements are processed, only the output is sent by the Web server to the Web browser. The PHP language statements are not included in the output sent to the browser, so the PHP code is secure and transparent to the user. For instance, in this simple PHP statement:

<?php echo “<p>Hello World</p>”; ?>

<?php is the PHP opening tag, and ?> is the closing tag. echo is a PHP instruction that tells PHP to output the upcoming text. The PHP software processes the PHP statement and outputs this:

<p>Hello World</p>

which is a regular HTML statement. This HTML statement is delivered to the user’s browser. The browser interprets the statement as HTML code and displays a Web page with one paragraph — Hello World. The PHP statement is not delivered to the browser, so the user never sees any PHP statements. PHP and the Web server must work closely together.

PHP is not integrated with all Web servers but does work with many of the popular Web servers. PHP is developed as a project of the Apache Software Foundation — thus, it works best with Apache. PHP also works with Microsoft IIS/PWS, iPlanet (formerly Netscape Enterprise Server), and others.

Although PHP works with several Web servers, it works best with Apache. If you can select or influence the selection of the Web server used in your organization, select Apache. By itself, Apache is a good choice. It’s free, open source, stable, and popular. It currently powers more than 60 percent of all Web sites, according to the Web server survey at www.netcraft.com. It runs on Windows, Linux, Mac OS, and most flavors of Unix.

MySQL and PHP, the Perfect Pair

MySQL and PHP are frequently used together. They’re often called the dynamic duo. MySQL provides the database part, and PHP provides the application part of your Web database application.

Advantages of the relationship

MySQL and PHP as a pair have several advantages:

They’re free. It’s hard to beat free for cost-effectiveness.

They’re Web oriented. Both were designed specifically for use on Web sites. Both have a set of features focused on building dynamic Web sites.

They’re easy to use. Both were designed to get a Web site up quickly.

They’re fast. Both were designed with speed as a major goal. Together they provide one of the fastest ways to deliver dynamic Web pages to users.

They communicate well with one another. PHP has built-in features for communicating with MySQL. You don’t need to know the technical details; just leave it to PHP.

How MySQL and PHP work together

PHP provides the application part, and MySQL provides the database part of a Web database application. You use the PHP language to write the programs that perform the application tasks. PHP can be used for simple tasks (such as displaying a Web page) or for complicated tasks (such as accepting and verifying data that a user typed into an HTML form). One of the tasks that your application must do is move data into and out of the database — and PHP has built-in features to use when writing programs that move data into and out of a MySQL database.

PHP statements are embedded in your HTML files with PHP tags. When the task to be performed by the application requires storing or retrieving data, you use specific PHP statements designed to interact with a MySQL database. You use one PHP statement to connect to the correct database, telling PHP where the database is located, its name, and the password needed to connect to it. The database doesn’t need to be on the same machine as your Web site; PHP can communicate with a database across a network. You use another PHP statement to send an SQL message to MySQL, giving MySQL instructions for the task you want to accomplish. MySQL returns a status message that shows whether it successfully performed the task. If a problem came up, it returns an error message. If your SQL message asked to retrieve some data, MySQL sends the data that you asked for, and PHP stores it in a temporary location where it’s available to you.

You then use one or more PHP statements to complete the application task. For instance, you can use PHP statements to display data that you retrieved. Or you might use PHP statements to display a status message in the browser, informing the user that the data was saved.

As an RDBMS, MySQL can store complex information. As a scripting language, PHP can perform complicated manipulations of data, on either data that you need to modify before saving it in the database or data that you retrieved from the database and need to modify before displaying or using it for another task. Together, PHP and MySQL can be used to build a sophisticated and complicated Web database application.

Keeping Up with PHP and MySQL Changes

PHP and MySQL are open source software. If you’ve used only software from major software publishers — such as Microsoft, Macromedia, or Adobe — you’ll find that open source software is an entirely different species. It’s developed by a group of programmers who write the code in their spare time, for fun and for free. There’s no corporate office.

Open source software changes frequently, rather than once every year or two like commercial software does. It changes when the developers feel that it’s ready. It also changes quickly in response to problems. When a serious problem is found — such as a security hole — a new version that fixes the problem can be released in days. You don’t receive glossy brochures or see splashy magazine ads for a year before a new version is released. Thus, if you don’t make the effort to stay informed, you could miss the release of a new version or be unaware of a serious problem with your current version.

Visit the PHP and MySQL Web sites often. You need to know the information that’s published there. Join the mailing lists, which often are high in traffic. When you first get acquainted with PHP and MySQL, the large number of mail messages on the discussion lists brings valuable information into your e-mail inbox; you can pick up a lot by reading those messages. And soon, you might be able to help others based on your own experience. At the very least, subscribe to the announcement mailing list, which delivers e-mail only occasionally. Any important problems or new versions are announced here. The e-mail that you receive from the announcement list contains information you need to know. So, right now, before you forget, hop over to the PHP and MySQL Web sites and sign up for a list or two at www.php.net/mailing-lists.php and lists.mysql.com.

PHP versions

The current version of PHP is PHP 5. Some existing applications still run PHP 4, but because you’re building your first PHP application, you should be using PHP 5.

PHP 6 is due to be released soon. Perhaps it has already been released by the time you’re reading this book. When PHP changes from version 5 to version 6, the following important changes will occur:

The setting for register_globals will no longer exist.

The setting for magic quotes will no longer exist.

The long arrays, such as HTTP_POST_VARS, will no longer exist. These arrays were commonly used in PHP 4.

If you’re ever converting scripts that ran under PHP 4 or 5 to run under PHP 6, you may need to make changes to the scripts, based on the preceding changes, before the scripts will run correctly under PHP 6. I explain these changes throughout the book where they apply to the techniques and procedures.

MySQL versions

MySQL 5.1 is the current version, as of this writing. MySQL 5.0 is also available. The examples and scripts in this book run equally well under either version. Some of the more advanced features of 5.1 may not be available on sites running 5.0, but none of those advanced features are discussed in this book.

MySQL 6 is also available for download on the MySQL Web site. However, at the time of this writing, version 6.0 is an alpha release and not suitable for working Web sites or for beginning developers.

You may occasionally find a Web site running MySQL 4.3.1. The examples and scripts in this book can execute properly on these sites as well. It is not wise to run a Web site using MySQL 4.3.0 or earlier.

Chapter 2

Setting Up Your Work Environment

In This Chapter

Accessing PHP and MySQL through company Web sites and Web hosting companies

Building your own Web site from scratch

Testing PHP and MySQL

Now that you’ve decided to use PHP and MySQL to build your interactive Web site, you can begin working on the site. Your first task is to set up the environment in which you’re going to build the site. This chapter describes how to set up your Web site environment with all the tools you need to build your Web database application.

Anatomy of a Web Site

Because you most likely have created simple Web sites before, you know what a Web site is. It’s a collection of text files that contain the HTML code that the browser reads to display the Web pages. The computer space where the files are stored is the physical location of your Web site.

Web users often talk about Web site visitors, but the term visitors is technically misleading. Visitors don’t actually visit a Web site. When a person types the address (called a URL or Uniform Resource Locator) of a Web site into a Web browser, the browser sends a request over the Internet, asking to view the Web page at that address. Software at the Web site, called a Web server, receives the request and responds by sending the requested Web page. The browser receives the Web page file and displays the Web page in the browser window.

To make your Web site available to the public, you place the text files containing HTML code on the Web site where users can access them. A Web database application is similar. The difference is that the files contain PHP code, as well as HTML code.

To provide the dynamic Web database applications discussed in this book, your Web site must have the following software:

A Web server: The software that delivers your Web pages to the world

MySQL: The RDBMS (Relational Database Management System) that will store information for your Web database application

PHP: The scripting language that you’ll use to write the programs that provide the dynamic functionality for your Web site

I describe these three tools in detail in Chapter 1.

Building a Web Site

As discussed in the previous section, a Web site is a collection of text files placed on a computer in a location where users can access them. Placing the Web site files where they can be accessed by the public is called publishing the Web site. However, this is the final step of building the Web site, not the first step. You don’t want to publish the Web site until it’s finished — a perfect Web site ready for public viewing.

To prevent the public from seeing your half-finished Web site, warts and all, you need to develop your Web site in a location that isn’t available to the public. While developing your Web site, you’ll be testing things and troubleshooting problems. You need to do this work in private.

Because you need to build your Web site in private and hold off on making it public until it’s finished and perfect, your work environment needs two sites:

Your Web site: The site where your published Web site is located. The location where the public views your Web site.

Your development site: The location where you develop your Web pages. When your pages are complete, you then move them to your Web site.

Your Web site publishes your Web pages to the world. Your development site shouldn’t be available for the world to see your errors and half-done Web pages. Your development site needs to be hidden from the world. Never publish your Web pages until they are complete and perfect.

You need to decide where you’re going to publish your Web site and where you’re going to develop it. The information you need to make these decisions is provided in the next few sections of this chapter.

Deciding Where to Publish Your Web Site

One of your first decisions is where to publish your Web site. You need to publish it on a computer that’s connected to the World Wide Web. The computer should also provide the tools you need, as discussed earlier: a Web server, PHP, and MySQL. The most common locations for publishing your Web site are

A Web site hosted by a Web hosting company: The Web site is located on the Web hosting company’s computer. The Web hosting company installs and maintains the Web site software and provides space on its computer where you can install the files for the Web site.

A Web site put up by a company on its own computer: The company — usually the company’s IT (Information Technology) department — installs and administers the Web site software. Your job, for the purposes of this book, is to program the Web site, either as an employee of the company or as a contractor.

A Web site that you set up yourself: You plan to install and maintain the Web site software yourself. It could be a Web site of your own that you’re building on your own computer, or it might be a Web site that you’re installing for a client on the client’s computer.

You’ll most likely publish your Web site on one of the first two options. For these options, you don’t need to know much about the administration and operation of the Web site software. The Web server, PHP, and MySQL are already installed, and the information you need to access them is provided by the company responsible for the Web site.

The third option requires that you install, set up, administer, and maintain the Web site software yourself. This option requires much more technical knowledge of computer software than the first two options, where others provide the software for you. However, the advantage of this option is that you have more control. You can set up the Web site software with the settings that you prefer.

In the next three sections, I describe the publishing options in more detail and provide the information you need to decide where to publish your Web site.

Using a Web hosting company

A Web hosting company provides everything that you need to put up a Web site, including the computer space and all the Web site software. You just create the files for your Web pages and move them to a location specified by the Web hosting company. Most small-to-medium-sized Web sites are hosted by Web hosting companies.

About a gazillion companies offer Web hosting services. Most charge a monthly fee (often quite small), and some are even free. (Most, but not all, of the free ones require you to display advertising.) Usually, the monthly fee varies depending on the resources provided for your Web site. For instance, a Web site with 2MB of disk space for your Web page files costs less than a Web site with 10MB of disk space.

When looking for a place to host your Web site, make sure that the Web hosting company offers the following:

PHP and MySQL: Not all companies provide these tools. You might have to pay more for a site with access to PHP and MySQL; sometimes you have to pay an additional fee for MySQL databases.

A recent version of PHP: Sometimes the PHP versions offered aren’t the most recent versions. As of this writing, PHP 6 is close to being released.

Until PHP 6 is released, two versions of PHP are generally available — PHP 4 and PHP 5. Even though PHP 5 has been out for several years, many Web sites still run PHP 4. PHP 4 is still supported because existing PHP 4 code does not always run perfectly under PHP 5. Many developers have not yet converted their code to run under PHP 5. However, the demise of PHP 4 is looming. Support for PHP 4 stopped at the end of 2007. There will be no more releases of PHP 4, and critical security fixes ended in late 2008. There is no reason for anyone developing new code to use PHP 4.