Specifications

Using MySQL
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ART II
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Previously, in our work with PHP, we used a flat file to store and retrieve data. When we
looked at this in Chapter 2, “Storing and Retrieving Data,” we mentioned that relational data-
base systems make a lot of these storage and retrieval tasks easier, safer, and more efficient in a
Web application. Now, having worked with MySQL to create a database, we can begin con-
necting this database to a Web-based front end.
In this chapter, we’ll explain how to access the Book-O-Rama database from the Web using
PHP. You’ll learn how to read from and write to the database, and how to filter potentially trou-
blesome input data.
Overall, we’ll look at
• How Web database architectures work
• The basic steps in querying a database from the Web
• Setting up a connection
• Getting information about available databases
• Choosing a database to use
• Querying the database
• Retrieving the query results
• Disconnecting from the database
• Putting new information in the database
• Making your database secure
• Other useful PHP—MySQL functions
• Other PHP-database interfaces
How Web Database Architectures Work
In Chapter 7, “Designing Your Web Database,” we outlined how Web database architectures
work. Just to remind you, here are the steps again:
1. A user’s Web browser issues an HTTP request for a particular Web page. For example,
the user might have requested a search for all the books written by Michael Morgan at
Book-O-Rama, using an HTML form. The search results page is called results.php.
2. The Web server receives the request for results.php, retrieves the file, and passes it to the
PHP engine for processing.
3. The PHP engine begins parsing the script. Inside the script is a command to connect to
the database and execute a query (perform the search for books). PHP opens a connec-
tion to the MySQL server and sends on the appropriate query.
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