AJAX Introduction

AJAX is about updating parts of a web page, without reloading the whole page.

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What is AJAX?

AJAX = Asynchronous JavaScript and XML.
AJAX is a technique for creating fast and dynamic web pages.
AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.
Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.
Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.

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How AJAX Works

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AJAX is Based on Internet Standards

AJAX is based on internet standards, and uses a combination of:

• XMLHttpRequest object (to exchange data asynchronously with a server)
• JavaScript/DOM (to display/interact with the information)
• CSS (to style the data)
• XML (often used as the format for transferring data)

	AJAX applications are browser- and platform-independent!

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Google Suggest

AJAX was made popular in 2005 by Google, with Google Suggest.
Google Suggest is using AJAX to create a very dynamic web interface: When you start typing in Google's search box, a JavaScript sends the letters off to a server and the server returns a list of suggestions.

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Start Using AJAX Today

In our PHP tutorial, we will demonstrate how AJAX can update parts of a web page, without reloading the whole page. The server script will be written in PHP.
If you want to learn more about AJAX, visit our AJAX tutorial.

PHP MySQL Introduction

With PHP, you can connect to and manipulate databases.

MySQL is the most popular database system used with PHP.

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What is MySQL?

• MySQL is a database system used on the web
• MySQL is a database system that runs on a server
• MySQL is ideal for both small and large applications
• MySQL is very fast, reliable, and easy to use
• MySQL supports standard SQL
• MySQL compiles on a number of platforms
• MySQL is free to download and use
• MySQL is developed, distributed, and supported by Oracle Corporation
• MySQL is named after co-founder Monty Widenius's daughter: My

The data in MySQL is stored in tables. A table is a collection of related data, and it consists of columns and rows.
Databases are useful when storing information categorically. A company may have a database with the following tables:

• Employees
• Products
• Customers
• Orders

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PHP + MySQL

• PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)

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Queries

A query is a question or a request.
We can query a database for specific information and have a recordset returned.
Look at the following query (using standard SQL):

SELECT LastName FROM Employees

The query above selects all the data in the "LastName" column from the "Employees" table.
To learn more about SQL, please visit our SQL tutorial.

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Download MySQL Database

If you don't have a PHP server with a MySQL Database, you can download MySQL for free here: http://www.mysql.com

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Facts About MySQL Database

One great thing about MySQL is that it can be scaled down to support embedded database applications. Maybe it is because of this many people think that MySQL can only handle small and medium-sized systems.
The truth is that MySQL is the de-facto standard database system for web sites with HUGE volumes of both data and end users (like Friendster, Yahoo, and Google).
Look at http://www.mysql.com/customers/ for an overview of companies using MySQL.

PHP 5 Introduction

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PHP scripts are executed on the server.

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What You Should Already Know

Before you continue you should have a basic understanding of the following:

• HTML
• CSS
• JavaScript

If you want to study these subjects first, find the tutorials on our Home page.

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What is PHP?

• PHP is an acronym for "PHP Hypertext Preprocessor"
• PHP is a widely-used, open source scripting language
• PHP scripts are executed on the server
• PHP costs nothing, it is free to download and use

	PHP is an amazing and popular language! It is powerful enough to be at the core of the biggest blogging system on the web (WordPress)! It is deep enough to run the largest social network (Facebook)! It is also easy enough to be a beginner's first server side language!

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What is a PHP File?

• PHP files can contain text, HTML, CSS, JavaScript, and PHP code
• PHP code are executed on the server, and the result is returned to the browser as plain HTML
• PHP files have extension ".php"

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What Can PHP Do?

• PHP can generate dynamic page content
• PHP can create, open, read, write, delete, and close files on the server
• PHP can collect form data
• PHP can send and receive cookies
• PHP can add, delete, modify data in your database
• PHP can restrict users to access some pages on your website
• PHP can encrypt data

With PHP you are not limited to output HTML. You can output images, PDF files, and even Flash movies. You can also output any text, such as XHTML and XML.

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Why PHP?

• PHP runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
• PHP is compatible with almost all servers used today (Apache, IIS, etc.)
• PHP supports a wide range of databases
• PHP is free. Download it from the official PHP resource: www.php.net
• PHP is easy to learn and runs efficiently on the server side