What You Should Already Know
Before you continue you should have a basic understanding of the following: * HTML/XHTML
If you want to study these subjects first, find the tutorials on our Home page.
What is PHP?
* PHP stands for PHP: Hypertext Preprocessor
* PHP is a server-side scripting language, like ASP
* PHP scripts are executed on the server
* PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.) * PHP is an open source software
* PHP is free to download and use
What is a PHP File?
* PHP files can contain text, HTML tags and scripts
* PHP files are returned to the browser as plain HTML
* PHP files have a file extension of ".php", ".php3", or ".phtml"
What is MySQL?
* MySQL is a database server
* MySQL is ideal for both small and large applications
* MySQL supports standard SQL
* MySQL compiles on a number of platforms
* MySQL is free to download and use
PHP + MySQL
* PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)
* PHP runs on different platforms (Windows, Linux, Unix, etc.) * PHP is compatible with almost all servers used today (Apache, IIS, etc.) * PHP is easy to learn and runs efficiently on the server side
Basic PHP Syntax
A PHP script always starts with <?php and ends with ?>. A PHP script can be placed anywhere in the document. On servers with shorthand-support, you can start a PHP script with <? and end with ?>. For maximum compatibility, we recommend that you use the standard form (<?php) rather than the shorthand form. <?php
A PHP file must have a .php extension.
A PHP file normally contains HTML tags, and some PHP scripting code. Below, we have an example of a simple PHP script that sends the text "Hello World" back to the browser: <html>
echo "Hello World";
Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another. There are two basic statements to output text with PHP: echo and print. In the example above we have used the echo statement to output the text "Hello World".
Comments in PHP
In PHP, we use // to make a one-line comment or /* and */ to make a comment block: <html>
//This is a comment
As with algebra, PHP variables are used to hold values or expressions. A variable can have a short name, like x, or a more descriptive name, like carName. Rules for PHP variable names:
* Variables in PHP starts with a $ sign, followed by the name of the variable * The variable name must begin with a letter or the underscore character * A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ ) * A variable name should not contain spaces
* Variable names are case sensitive (y and Y are two different variables)
Creating (Declaring) PHP Variables
PHP has no command for declaring a variable.
A variable is created the moment you first assign a value to it: $myCar="Volvo";
After the execution of the statement above, the variable myCar will hold the value Volvo. Tip: If you want to create a variable without assigning it a value, then you assign it the value of null. Let's create a variable containing a string, and a variable containing a number: <?php
Note: When you assign a text value to a variable, put quotes around the value.
PHP is a Loosely Typed Language
In PHP, a variable does not need to be declared before adding a value to it. In the example above, notice that we did not have to tell PHP which data type the variable is. PHP automatically converts the variable to the correct data...
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