Use PHP to access MySQL(1)_PHP tutorial

In this chapter we will learn how to store information in a database and display it in a Web page. We have previously installed MySQL, a relational database engine, and PHP, a server-side scripting language, and learned basic knowledge about them. After studying this chapter, we will understand how to use these two new tools to build a database-driven website!

Review

Before we continue, it should be valuable to review the purpose of our learning. We now have two powerful new tools in our system: the scripting language PHP and the database engine MySQL. It's important to figure out how the two work together.

The essence of a database-driven website is to allow the content of the site to exist in a database, and to dynamically generate Web pages through this database so that our visitors can display it through a standard Web browser. So at one end of your system is a browser who visits your site. He obtains a standard HTML formatted Web page and displays it in a Web browser by accessing HTTP://WWW.YOURSITE.COM. On the other side of your system is the content of your site stored in one or several data tables in a MySQL database that only understands how to respond to SQL queries (commands).

The PHP scripting language plays the role of liaison between the two. Using PHP, you can write a standard HTML "template". This "template" determines the appearance of your site (including pictures and page design). At this point the content belongs to this "template". You can use some PHP code to connect to the MySQL database and use SQL queries to get the data and display it in its corresponding location. The SQL queries here are the same ones we used in Chapter 2 The same is true when creating a joke data table.

Now you should have a clear idea of ​​what happens when a visitor visits a page on your database-driven website:

The visitor’s web browser Use a standard URL to request this page.

The web server software (Apache, IIS or other) recognizes that the requested page is a PHP script and uses its PHP plug-in to interpret it before responding to the page request.

Some PHP commands (that we haven’t learned yet) will connect to the MySQL database and request the database for the content belonging to this web page.

The MySQL database responds and sends the requested content to the PHP script.

The PHP script stores the content into one or several PHP variables and outputs it as part of the web page using the familiar echo function.

The PHP plugin completes processing and returns a copy of the resulting HTML to the web server.

The web server sends this HTML copy to the web browser, which will be a standard HTML file, except that it does not come directly from an HTML file, but from the output provided by the PHP plug-in.

Connecting to MySQL with PHP

Before we get the content contained in our web page from our MySQL database, we first have to know how to set up with MySQL connect. In Chapter 2, we used a program called mysql to make such a connection. PHP does not require such a program, support for connecting to MySQL is built into the language. The following function is used to establish such a connection:

mysql_connect( <br>

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