Php

PHP Sheet

Introduction

PHP is a server-side scripting language designed for web development. It is widely used to create dynamic and interactive web applications. This cheat-sheet covers essential PHP syntax and concepts to help you get started with PHP.

Installation

To use PHP, you need to have it installed on your web server. Follow these steps to install PHP:

Windows

1. Download PHP from the official website: https://windows.php.net/download/
2. Extract the downloaded files to a directory of your choice.
3. Add the PHP directory to your system's PATH environment variable.

macOS

PHP comes pre-installed on macOS. You can check the installed version using the terminal:

php -v

Linux (Ubuntu)

1. Install PHP using the package manager:

sudo apt update sudo apt install php

Running PHP Code

1. Create a new PHP file with the .php extension (e.g., index.php).
2. Add your PHP code inside the file.

To run the PHP code, you have several options:

Using a Web Server:

Place the PHP file in your web server's document root (e.g., /var/www/html) and access it through a web browser.

Using PHP Built-in Server:

Open the terminal, navigate to the directory containing the PHP file, and run:

php -S localhost:8000

Then, access the PHP file in your browser at localhost:8000.

Using Command-Line Interpreter:

Open the terminal, navigate to the directory containing the PHP file, and run:

php your_file.php

Basic PHP Syntax

Variables

$name = "John"; 
$age = 30;

Output

echo "Hello, World!";

Strings

$name = "John"; 
$message = "Hello, $name!";

Arrays

$fruits = array("Apple", "Banana", "Orange");

Conditionals

if ($age >= 18) {    
	echo "You are an adult."; 
} elseif ($age >= 13) {     
	echo "You are a teenager."; 
} else {     
	echo "You are a child."; 
}

Loops

for ($i = 1; $i <= 5; $i++) {     
	echo "$i "; 
}  while ($x <= 10) {     
	echo "$x ";     $x++; 
}

Functions

function greet($name) {     
	echo "Hello, $name!"; 
}  

greet("John");

Working with Forms

HTML Form

<form action="process_form.php" method="post">   
	<input type="text" name="username" placeholder="Username">   
	<input type="password" name="password" placeholder="Password">   
	<input type="submit" value="Submit"> 
</form>

Processing Form Data

// process_form.php  
if ($_SERVER["REQUEST_METHOD"] == "POST") {     
	$username = $_POST["username"];     
	$password = $_POST["password"];      
	// Perform validation and further processing 
}

Working with Databases

Connecting to MySQL Database

$servername = "localhost"; 
$username = "db_user"; 
$password = "db_password"; 
$dbname = "database_name";  

$conn = new mysqli($servername, $username, $password, $dbname);  
if ($conn->connect_error) {     
	die("Connection failed: " . $conn->connect_error); 
}

Querying Data

$sql = "SELECT * FROM users"; 
$result = $conn->query($sql);  

if ($result->num_rows > 0) {     
	while ($row = $result->fetch_assoc()) {         
		echo "Name: " . $row["name"] . " - Email: " . $row["email"] . "<br>";
	} 
} else {     
	echo "0 results"; 
}

Basic SQL Database Operations

Add Data

$sql = "INSERT INTO table_name (column1, column2, column3) VALUES ('value1', 'value2', 'value3')"; 
if ($conn->query($sql) === TRUE) {     
	echo "New record created successfully"; 
} else {     
	echo "Error: " . $sql . "<br>" . $conn->error; 
}

Change Data

$sql = "UPDATE table_name SET column1='new_value1' WHERE condition"; 
if ($conn->query($sql) === TRUE) {     
	echo "Record updated successfully"; 
} else {     
	echo "Error updating record: " . $conn->error; 
}

Check Data

$sql = "SELECT * FROM table_name WHERE condition"; 
$result = $conn->query($sql);  
if ($result->num_rows > 0) {     
	// Output data 
} else {     
	echo "0 results"; 
}

Delete Data

$sql = "DELETE FROM table_name WHERE condition"; 
if ($conn->query($sql) === TRUE) {     
	echo "Record deleted successfully"; 
} else {     
	echo "Error deleting record: " . $conn->error; 
}

Get Data

$sql = "SELECT * FROM table_name"; 
$result = $conn->query($sql);  
if ($result->num_rows > 0) {     
	while($row = $result->fetch_assoc()) {         
		// Output data     
	} 
} else {     
	echo "0 results"; 
}

Conclusion

This cheat-sheet covers the basic usage and syntax of PHP for web development. PHP is a powerful language that allows you to create dynamic and interactive web applications. As you become more comfortable with PHP, you can explore its extensive documentation for more advanced features and functionalities. Happy coding with PHP!