Introduction to PHP

Overview of PHP

• PHP is a server-side scripting language used to build dynamic web pages.
• Runs on a server, not in the user's web browser.
• Despite claims that PHP is dead, it powers around 70% of known websites.
• Preferred by developers for its speed, simplicity, and flexibility.

History of PHP

• Released in 1995.
• Originally "Personal Home Page", later changed to "PHP: Hypertext Preprocessor".
• Evolved organically, now widely used.
• Mascot is an elephant named "Ella".

Basic PHP Functionality

• A browser sends a request to a server, PHP processes it, and returns HTML to the browser.
• Commonly used with relational databases like MySQL, PostgreSQL, and Oracle.

Setting Up PHP Environment

Required Software

• ZAMP: Cross-platform web server solution stack (Apache, MySQL, PHP).
• VS Code: Popular text editor for writing code.

Installation Steps

1. Download ZAMP from apachefriends.org.
2. Follow installer prompts and select necessary components.
3. Start Apache and MySQL services from ZAMP control panel.
4. Download and install Visual Studio Code from code.visualstudio.com.
5. Create a folder in the ZAMP directory for your website files.

Writing PHP Code

Creating PHP Files

• PHP code is written within <?php and ?> tags.
• Use echo to display messages.
• Example: <?php echo "I like pizza"; ?>

Variables in PHP

• Variables are declared with a $ sign.
• Data types include:
  • Strings, Integers, Floats, Booleans.
• Example of variable declaration:

  $name = "Your Name";  
  

Basic Arithmetic in PHP

Arithmetic Operators

• Addition (+), Subtraction (-), Multiplication (*), Division (/), Exponentiation (**), Modulus (%).

Increment and Decrement Operators

• ++ to increment, -- to decrement.
• Example of incrementing a variable: ++$counter;

Operator Precedence

• Parentheses first, then exponents, multiplication and division, addition and subtraction.

Getting User Input

Handling Forms

• Use $_GET and $_POST to retrieve form data.
• Example of a simple form submission using POST method.

PHP Super Globals

• Super Globals are built-in variables in PHP that are always accessible.
• Common Super Globals:
  • $_GET, $_POST, $_SESSION, $_COOKIE, $_SERVER.

PHP Sessions and Cookies

Cookies

• Store user data in the browser using setcookie().
• Can expire after a set time.

Sessions

• Store user information across multiple pages using session_start().
• Session data is stored on the server and identified by a session ID.

Connecting to a MySQL Database

MySQLi Extension

• Use MySQLi to connect to MySQL databases in PHP.
• Example of establishing a connection and handling errors with try/catch.

Creating a MySQL Table

• Use phpMyAdmin to create tables and manage your database.
• Define columns and set data types (e.g., INT, VARCHAR, DATETIME).

CRUD Operations

Inserting Data

• Use SQL INSERT queries to add data to the database.
• Hash passwords before storing them.

Retrieving Data

• Use SQL SELECT queries to fetch data from the database.
• Handle multiple rows using loops.

Conclusion

• PHP is a powerful language for web development, providing dynamic web page capabilities and database interactions.
• It's crucial to understand variables, arithmetic, sessions, cookies, and database connections to leverage its full potential.