PHP (PHP: Hypertext Preprocessor) is a server-side scripting language embedded in HTML, used for dynamic content, database management, session tracking, and e-commerce site development. It supports databases like MySQL, PostgreSQL, Oracle, and SQL Server.
Displaying "Hello, World!" in PHP:
<?php echo "Hello, World!"; ?>PHP code is processed on the server, and only the HTML output is sent to the client.
Comments help in debugging and understanding code. HTML comments:
<!-- Insert comment here -->PHP supports multiple comment styles:
// Single-line comment# Shell-style comment/* Multi-line comment */Using comments makes code easier to maintain and understand.
Variables store data values.
Example:
$city = "New Delhi";$ followed by a meaningful name.Example of a variable assignment:
<?php
$greeting = "Hello";
?>PHP variables can hold different data types like strings, integers, and floating-point numbers.
They are dynamically typed and can store any data type.
$name = "Suraj John";
$age = 2;Strings are enclosed in quotes, while numbers are not.
$, followed by a valid name.PHP is case-sensitive, meaning variable names must match exactly.
Example:
<?php
$mynameis = "Suraj John";
echo $Mynameis;
?>Incorrect capitalization results in an error:
Warning: Undefined variable: Mynameis in samplecode.php on line 3Example:
Using your HTML editor, enter the following:
<?php
$firstName = "Suraj";
$lastName = "John";
echo "Hello, " . $firstName . " " . $lastName . "!";
?>Output:
Hello, Suraj John!
To destroy a variable, pass the variable to PHP's unset() function, as in the following example:
<?php
$name = "Smith";
echo $name;
// unset() function destroys the variable reference.
unset($name);
?>Output:
Smith
In the above example, the variable $name holds the value "Smith". The unset() function deletes this variable. Since unset() is called after echo, the first output is "Smith".
Now, if we try to use the variable after unset(), we get the following error:
PHP Notice: Undefined variable
A constant is an identifier for a fixed value that cannot be changed during the execution of the script.
$ sign like variables.constant() function.define() function, which takes two arguments: the constant's name and its value.$ prefix.Syntax:
<?php
define('SITE_NAME', 'MyWebsite');
?>
<?php
define("MAX_USERS", 100);
define("SITE_URL", "https://aksharacs.netlify.app");
echo "Maximum users allowed: " . MAX_USERS . "<br>";
echo "Visit us at: " . constant("SITE_URL"); // Using constant() function
?>
Only scalar data types (boolean, integer, float, and string) can be stored in constants.
$ prefix, whereas variables do.define(), while variables are assigned with =.<?php
// Valid constant names
define("APP_VERSION", "1.0.5");
define("ALLOW_GUESTS", true);
define("MAX_SCORE", 500);
// Invalid constant names
define("123RANK", "Top Player"); // Starts with a number (Invalid)
define("__CONFIG__", "Settings"); // Reserved naming pattern (Invalid)
?>
gettype() function returns the data type of a variable.var_dump() function displays a variable's value, data type, and size.<?php
$age = 25; // Integer
$price = 49.99; // Float
$name = "Akshara"; // String
$isMember = true; // Boolean
var_dump($age, $price, $name, $isMember);
?>
Output:
int(25) float(49.99) string(5) "Akshara" bool(true)
These types store a single value.
<?php
$score = 90; // Integer
$temperature = 36.6; // Float
$greeting = "Good Morning"; // String
$isAvailable = false; // Boolean
echo "Score: " . $score . "<br>";
echo "Temperature: " . $temperature . "<br>";
echo "Greeting: " . $greeting . "<br>";
echo "Availability: " . ($isAvailable ? "Yes" : "No");
?>
An integer is a whole number with no decimal or fractional part. It can be positive, negative, or zero.
The size of an integer depends on the platform, typically 32-bit (max value: 2,147,483,647) or 64-bit (max value: ~9E18).
<?php
$age = 30; // Integer
var_dump($age);
?>
Output:
int(30)
A float (or double) is a number that includes a decimal point or is written in exponential form.
<?php
$temperature = 98.6; // Float
var_dump($temperature);
?>
Output:
float(98.6)
Floats are commonly used for precise calculations, such as scientific measurements or financial applications.
A string is a sequence of characters used for storing and manipulating text, including letters, numbers, and special symbols. Strings can be enclosed in single or double quotes.
<?php
$string1 = "Hello, World!";
$string2 = 'PHP is powerful!';
?>
Single-quoted strings are treated literally, while double-quoted strings interpret variables and escape sequences.
<?php
$name = "John";
echo 'Hello, $name!'; // Outputs: Hello, $name!
echo "Hello, $name!"; // Outputs: Hello, John!
?>
Some useful escape sequences in PHP strings:
<?php
echo "Hello\nWorld"; // Outputs Hello (new line) World
?>
PHP provides a variety of functions to work with strings, including concatenation, length calculation, searching, and manipulation.
String concatenation is the process of joining two or more strings together. In PHP, we use the . (dot) operator to concatenate strings.
<?php
$name = "John";
$greeting = "Hello, " . $name . "!";
echo $greeting; // Output: Hello, John!
?>
Concatenation using .= operator:
<?php
$message = "Welcome";
$message .= " to PHP!";
echo $message; // Output: Welcome to PHP!
?>
PHP provides the strlen() function to determine the length of a string.
<?php
$text = "Hello, World!";
echo strlen($text); // Output: 13
?>
To find the position of a substring inside a string, use the strpos() function. It returns the index of the first occurrence of the substring or false if not found.
<?php
$text = "Hello, World!";
$position = strpos($text, "World");
echo $position; // Output: 7
?>
str_replace() – Replace Substring in a StringReplaces all occurrences of a search string with a replacement string.
<?php
$text = "I love JavaScript!";
$newText = str_replace("JavaScript", "PHP", $text);
echo $newText; // Output: I love PHP!
?>
substr() – Extract Part of a StringExtracts a portion of a string based on the starting index and optional length.
<?php
$text = "Hello, World!";
echo substr($text, 7, 5); // Output: World
?>
strtolower() and strtoupper() – Change Case of StringsConverts a string to lowercase or uppercase.
<?php
$text = "Hello, World!";
echo strtolower($text); // Output: hello, world!
echo strtoupper($text); // Output: HELLO, WORLD!
?>
trim() – Remove WhitespaceRemoves leading and trailing whitespace from a string.
<?php
$text = " Hello, World! ";
echo trim($text); // Output: Hello, World!
?>
strrev() – Reverse a StringReverses the characters in a string.
<?php
$text = "PHP";
echo strrev($text); // Output: PHP
?>
explode() – Convert a String to an ArraySplits a string into an array using a specified delimiter.
<?php
$text = "apple,banana,grape";
$fruits = explode(",", $text);
print_r($fruits); // Output: Array ( [0] => apple [1] => banana [2] => grape )
?>
implode() – Convert an Array to a StringJoins array elements into a single string with a specified separator.
<?php
$fruits = ["apple", "banana", "grape"];
echo implode(" | ", $fruits); // Output: apple | banana | grape
?>
. for string concatenation.strlen() gets string length.strpos() finds a substring.str_replace() replaces parts of a string.substr() extracts substrings.strtolower() and strtoupper() change case.trim() removes whitespace.strrev() reverses a string.explode() splits a string into an array.implode() joins an array into a string.These functions make PHP string manipulation easy and efficient!
A Boolean represents a binary state, either true (1) or false (0).
<?php
$enabled = true;
$disabled = false;
var_dump($enabled, $disabled);
?>
Output:
bool(true) bool(false)
An array holds multiple values in a single variable. It can store numbers, strings, or objects.
<?php
$fruits = array("Apple", "Banana", "Cherry");
var_dump($fruits);
?>
Output:
array(3) { [0]=> string("Apple") [1]=> string("Banana") [2]=> string("Cherry") }
An indexed array is a simple array where elements are stored with a numeric index starting from 0.
<?php
$fruits = array("Apple", "Banana", "Cherry");
// Accessing elements
echo $fruits[0]; // Output: Apple
echo "<br>";
// Looping through an indexed array
foreach ($fruits as $fruit) {
echo $fruit . "<br>";
}
?>
An associative array uses named keys instead of numeric indices. It is useful for storing data in key-value pairs.
<?php
$person = array("name" => "John", "age" => 2, "city" => "Banglore");
// Accessing elements
echo "Name: " . $person["name"] . "<br>";
echo "Age: " . $person["age"] . "<br>";
echo "City: " . $person["city"] . "<br>";
// Looping through an associative array
foreach ($person as $key => $value) {
echo "$key : $value <br>";
}
?>
A multidimensional array is an array that contains one or more arrays. It is useful for storing complex data structures.
<?php
$students = array(
array("name" => "Akshara", "age" => 5, "grade" => "A"),
array("name" => "Aron", "age" => 5, "grade" => "B"),
array("name" => "Suraj", "age" => 2, "grade" => "A")
);
// Accessing elements
echo "Student 1: " . $students[0]["name"] . " - Age: " . $students[0]["age"] . " - Grade: " . $students[0]["grade"] . "<br>";
echo "<br>";
// Looping through a multidimensional array
foreach ($students as $student) {
echo "Name: " . $student["name"] . " - Age: " . $student["age"] . " - Grade: " . $student["grade"] . "<br>";
}
?>
These array types allow flexible data storage and manipulation in PHP.
The special Data type "NULL" represents a variable with no value.
<?php
$variable = NULL;
if (is_null($variable)) {
echo "The variable is NULL";
}
?>
Output:
The variable is NULL
The special resource type is not an actual data type. It is the storing of a reference to functions and resources external to PHP.
A common example of using the resource data type is handling files.
<?php
$file = fopen("example.txt", "r");
if ($file) {
echo "File opened successfully";
fclose($file);
}
?>
Output:
File opened successfully
PHP allows reading user input from the console using standard input.
<?php
echo "Enter your name: ";
$handle = fopen("php://stdin", "r");
$name = trim(fgets($handle));
echo "Hello, $name!";
?>
Example Console Input & Output:
Enter your name: John
Hello, John!
Using different types of operators, values are assigned to variables.
PHP supports more than 50 such operators, ranging from operators for arithmetical operations to operators for logical comparison and bitwise calculations.
This section discusses the most commonly used operators.
+, -, *, /, and % are arithmetic operators.
+ means addition
<?php
$x = 10;
$y = 5;
$z = $x + $y;
echo "Addition: " . $z;
?>
- means subtraction
<?php
$z = $x - $y;
echo "Subtraction: " . $z;
?>
* means multiplication
<?php
$z = $x * $y;
echo "Multiplication: " . $z;
?>
/ means division
<?php
<?php
$z = $x / $y;
echo "Division: " . $z;
?>
% means modulus or remainder
<?php
$z = $x % $y;
echo "Modulus: " . $z;
?>
The basic assignment operator is (=) sign.
Single equal sign means "assigned to". It does not mean "equal to".
Double equal to sign (==) means "equal to".
Other assignment operators include +=, -=, and .=:
<?php
$x = 10;
$x += 5; // Equivalent to $x = $x + 5
echo "x after += : " . $x;
?>
<?php
$x -= 3; // Equivalent to $x = $x - 3
echo "x after -= : " . $x;
?>
<?php
$txt = "Hello";
$txt .= " World!"; // Concatenation
echo $txt;
?>
This operator is used to compare two values.
<?php
$x = 4;
$y = 10;
var_dump($x == $y); // false
var_dump($x != $y); // true
var_dump($x > $y); // false
var_dump($x < $y); // true
var_dump($x >= $y); // false
var_dump($x <= $y); // true
?>
These operators determine the status of conditions, often used in if-else and loops.
<?php
$x = true;
$y = false;
var_dump(!$x); // false
var_dump($x && $y); // false
var_dump($x || $y); // true
?>
This operator adds or subtracts from a variable.
<?php
$x = 5;
echo ++$x; // Pre-increment, outputs 6
echo $x++; // Post-increment, outputs 6 then increases to 7
echo --$x; // Pre-decrement, outputs 6
echo $x--; // Post-decrement, outputs 6 then decreases to 5
?>
Expressions are fundamental in PHP, as almost everything is an expression. An expression is anything that has a value.
Constants, variables, and functions are the simplest expressions. For example:
<?php
$a = 5; // 5 is an expression
$b = $a; // $a is also an expression with the value 5
?>
Functions return expressions based on their return values:
<?php
function foo() {
return 5;
}
$c = foo(); // Same as $c = 5
?>
Assignments also produce a value. For example:
<?php
$b = ($a = 5); // Same as $a = 5; $b = 5;
?>
These operators modify values and return expressions based on their type:
<?php
$a = 5;
$b = $a++;
$c = ++$a;
?>
Expressions evaluating to TRUE or FALSE:
<?php
$x = 4;
$y = 10;
var_dump($x == $y); // false
var_dump($x === $y); // false, different types
?>
These modify variables using arithmetic operations:
<?php
$a = 5;
$a += 3; // Equivalent to $a = $a + 3;
?>
Conditional shorthand:
<?php
$result = ($a > $b) ? "A is greater" : "B is greater";
?>
Example combining multiple expressions:
<?php
function double($i) {
return $i * 2;
}
$b = $a = 5;
$c = $a++;
$d = ++$b;
$f = double($d++);
$g = double(++$e);
$h = $g += 10;
?>
PHP provides various statements to handle decision-making:
<?php
$score = 85;
if ($score >= 90) {
echo "Excellent!";
} elseif ($score >= 75) {
echo "Good job!";
} else {
echo "Keep trying!";
}
?>
<?php
$day = "Tuesday";
switch ($day) {
case "Monday":
echo "Start of the work week.";
break;
case "Friday":
echo "Weekend is near!";
break;
default:
echo "Another regular day.";
}
?>
Loops help execute code multiple times:
<?php
for ($i = 1; $i <= 5; $i++) {
echo "Number: $i <br>";
}
?>
<?php
$i = 3;
while ($i > 0) {
echo "Countdown: $i <br>";
$i--;
}
?>
<?php
$x = 1;
do {
echo "Iteration: $x <br>";
$x++;
} while ($x <= 3);
?>
<?php
$colors = ["Red", "Green", "Blue"];
foreach ($colors as $color) {
echo "Color: $color <br>";
}
?>
Break exits the loop early, and Continue skips an iteration.
<?php
for ($i = 1; $i <= 5; $i++) {
if ($i == 3) break;
echo "Value: $i <br>";
}
?>
<?php
for ($i = 1; $i <= 5; $i++) {
if ($i == 3) continue;
echo "Value: $i <br>";
}
?>
Functions in PHP are reusable blocks of code that take input (parameters), process it, and return a result.
PHP provides many built-in functions, such as strlen() and array_push(), but you can also define your own functions.
To define a function, use the function keyword. Below is an example:
<?php
function greetUser() {
echo "Hello, welcome to PHP functions!";
}
greetUser();
?>
Functions can accept parameters to work with different values dynamically.
<?php
function greet($name) {
echo "Hello, $name!";
}
greet("Alice");
?>
When passing by reference, the original variable is modified.
<?php
function increaseByTen(&$number) {
$number += 10;
}
$value = 5;
increaseByTen($value);
echo "Updated value: $value"; // Output: 15
?>
Functions can return values using the return statement.
<?php
function multiply($a, $b) {
return $a * $b;
}
$result = multiply(4, 5);
echo "Multiplication result: $result";
?>
You can provide default values for parameters if they are not passed during function calls.
<?php
function greetAgain($name = "Guest") {
echo "Hello, $name!";
}
greetAgain(); // Output: Hello, Guest!
greetAgain("Bob"); // Output: Hello, Bob!
?>
You can call functions dynamically using variable function names.
<?php
function sayHello() {
echo "Hello, dynamic world!";
}
$func = "sayHello";
$func();
?>
PHP provides various functions to handle files, allowing us to create, open, read, write, append, and delete files. Below are the different file operations explained with examples.
To create a file, we use the fopen() function with the mode 'w'. If the file does not exist, it is created automatically.
<?php
$file = 'example.txt';
$handle = fopen($file, 'w') or die('Cannot create file');
fclose($handle);
?>
Files can be opened in different modes such as 'r' (read), 'w' (write), and 'a' (append).
<?php
$file = 'example.txt';
$handle = fopen($file, 'r') or die('Cannot open file');
fclose($handle);
?>
We use fread() to read the file content.
<?php
$file = 'example.txt';
$handle = fopen($file, 'r');
$content = fread($handle, filesize($file));
fclose($handle);
echo $content;
?>
We use fwrite() to write data into a file.
<?php
$file = 'example.txt';
$handle = fopen($file, 'w');
fwrite($handle, 'Hello, PHP File Handling!');
fclose($handle);
?>
To add content without overwriting, we use mode 'a' (append).
<?php
$file = 'example.txt';
$handle = fopen($file, 'a');
fwrite($handle, "\nAppending new data.");
fclose($handle);
?>
Always close a file after performing operations using fclose().
<?php
fclose($handle);
?>
To delete a file, we use the unlink() function.
<?php
$file = 'example.txt';
unlink($file);
?>
Forms are essential in web applications for collecting user input, such as login details, registration data, feedback, and file uploads.
<form method="post" action="process.php">
<label for="username">Enter your name:</label >
<input type="text" id="username" name="username" >
<input type="submit" value="Submit">
</form >
The action attribute specifies where the form data should be sent after submission.
In this example:
POST method.
process.php for handling.
When the form is submitted, it sends the data to process.php, which processes and displays the result.
<?php
// Check if form is submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Get the submitted value
$username = $_POST['username'];
// Display the result safely
echo "<h1>Hello, " . htmlspecialchars($username) . "!</h1>";
}
?>
The request method determines how form data is sent to the server. PHP checks this using:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Process the form
}
?>
This ensures that the script runs **only when** the form is submitted using the **POST** method.
In PHP, you can get the form data using the $_POST superglobal:
<?php
$username = $_POST['username'];
?>
This retrieves the value entered in the <input type="text"> field with **name="username"**.
To display the user's input, use:
<?php
echo "<h1>Hello, " . htmlspecialchars($username) . "!</h1>";
?>
Why use htmlspecialchars()?
<, >, and &.| Action Value | Description |
|---|---|
action="process.php" |
Sends data to process.php in the same directory. |
action="/submit-form.php" |
Sends data to a PHP script in the root directory. |
action="https://example.com/handle.php" |
Sends data to an external server. |
action="" (empty) |
Submits data to the **same page** that contains the form. |
action attribute determines **where** the form data is sent.process.php script handles and processes the form data.htmlspecialchars() prevents **security risks** like XSS.<input type="text">)Used for entering text.
<form method="post">
<label for="fullname">Full Name:</label>
<input type="text" id="fullname" name="fullname" placeholder="Enter your name">
<button type="submit">Submit</button>
</form>
The following PHP code retrieves and displays the entered full name:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$fullname = $_POST['fullname'];
echo "<p><strong>Full Name:</strong> " . htmlspecialchars($fullname) . "</p>";
}
?>
<input type="password">)Used for entering passwords securely.
<form method="post">
<label for="password">Password:</label>
<input type="password" id="password" name="password">
<button type="submit">Submit</button>
</form>
The following PHP code retrieves and displays the entered password:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$password = $_POST['password'];
echo "<p><strong>Password:</strong> " . htmlspecialchars($password) . "</p>";
}
?>
<input type="radio">)Used for selecting one option from multiple choices.
<form method="post">
<label>
<input type="radio" name="gender" value="Male"> Male
</label>
<label>
<input type="radio" name="gender" value="Female"> Female
</label>
<button type="submit">Submit</button>
</form>
The following PHP code retrieves and displays the selected gender:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$gender = isset($_POST['gender']) ? $_POST['gender'] : "Not selected";
echo "<p><strong>Gender:</strong> " . htmlspecialchars($gender) . "</p>";
}
?>
<input type="checkbox">)Used for selecting multiple options.
<form method="post">
<label>
<input type="checkbox" name="hobbies[]" value="Reading"> Reading
</label>
<label>
<input type="checkbox" name="hobbies[]" value="Sports"> Sports
</label>
<button type="submit">Submit</button>
</form>
The following PHP code retrieves and displays the selected hobbies:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$hobbies = isset($_POST['hobbies']) ? implode(", ", $_POST['hobbies']) : "No hobbies selected";
echo "<p><strong>Hobbies:</strong> " . htmlspecialchars($hobbies) . "</p>";
}
?>
<select>)Used for selecting a single value.
<form method="post">
<label for="country">Country:</label>
<select id="country" name="country">
<option value="USA">USA</option>
<option value="India">India</option>
</select>
<button type="submit">Submit</button>
</form>
The following PHP code retrieves and displays the selected country:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$country = $_POST['country'];
echo "<p><strong>Country:</strong> " . htmlspecialchars($country) . "</p>";
}
?>
<input type="file">)Used to upload files.
<form method="post" enctype="multipart/form-data">
<label for="profile_picture">Upload Profile Picture:</label>
<input type="file" id="profile_picture" name="profile_picture">
<button type="submit">Upload</button>
</form>
The following PHP code handles file uploads:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST" && !empty($_FILES['profile_picture']['name'])) {
$file_name = $_FILES['profile_picture']['name'];
$file_tmp = $_FILES['profile_picture']['tmp_name'];
move_uploaded_file($file_tmp, "uploads/" . $file_name);
echo "<p><strong>Uploaded File:</strong> " . htmlspecialchars($file_name) . "</p>";
} else {
echo "<p>No file uploaded.</p>";
}
?>
<textarea>)Used for multi-line text input.
<form method="post">
<label for="comments">Comments:</label>
<textarea id="comments" name="comments" rows="4" cols="40"></textarea>
<button type="submit">Submit</button>
</form>
The following PHP code retrieves and displays the entered comments:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$comments = $_POST['comments'];
echo "<p><strong>Comments:</strong> " . nl2br(htmlspecialchars($comments)) . "</p>";
}
?>
<input type="hidden">)Used to send hidden values.
<form method="post">
<input type="hidden" name="token" value="12345">
<button type="submit">Submit</button>
</form>
The following PHP code retrieves and displays the hidden field value:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$token = $_POST['token'];
echo "<p><strong>Token:</strong> " . htmlspecialchars($token) . "</p>";
}
?>
<input type="submit">, <input type="reset">, <button>)Used for submitting and resetting forms.
<form method="post">
<input type="submit" name="submit" value="Submit">
<input type="reset" value="Reset">
<button type="submit" name="custom_button" value="clicked">Click Me</button>
</form>
The following PHP code determines which button was clicked:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
if (isset($_POST['submit'])) {
echo "<p><strong>Action:</strong> Submit button clicked</p>";
}
if (isset($_POST['custom_button'])) {
echo "<p><strong>Action:</strong> Custom button clicked</p>";
}
}
?>
<form method="post" action="register.php" enctype="multipart/form-data">
<h2>Registration Form</h2>
Full Name: <input type="text" name="fullname"><br><br>
Password: <input type="password" name="password"><br><br>
Gender:
<input type="radio" name="gender" value="Male"> Male
<input type="radio" name="gender" value="Female"> Female<br><br>
Hobbies:
<input type="checkbox" name="hobbies[]" value="Reading"> Reading
<input type="checkbox" name="hobbies[]" value="Traveling"> Traveling
<input type="checkbox" name="hobbies[]" value="Music"> Music<br><br>
Country:
<select name="country">
<option value="USA">USA</option>
<option value="India">India</option>
</select><br><br>
Profile Picture: <input type="file" name="profile_picture"><br><br>
Comments:<br>
<textarea name="comments" rows="4" cols="30"></textarea><br><br>
<input type="hidden" name="token" value="abc123">
<input type="submit" value="Register">
<input type="reset" value="Reset">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Getting values
$fullname = $_POST['fullname'];
$password = $_POST['password'];
$gender = isset($_POST['gender']) ? $_POST['gender'] : "Not selected";
$hobbies = isset($_POST['hobbies']) ? implode(", ", $_POST['hobbies']) : "No hobbies selected";
$country = $_POST['country'];
$comments = $_POST['comments'];
$token = $_POST['token'];
// Handling File Upload
if (!empty($_FILES['profile_picture']['name'])) {
$file_name = $_FILES['profile_picture']['name'];
move_uploaded_file($_FILES['profile_picture']['tmp_name'], "uploads/" . $file_name);
} else {
$file_name = "No file uploaded";
}
// Displaying submitted data
echo "<h2>Registration Details</h2>";
echo "Full Name: $fullname<br>";
echo "Password: $password<br>";
echo "Gender: $gender<br>";
echo "Hobbies: $hobbies<br>";
echo "Country: $country<br>";
echo "Comments: $comments<br>";
echo "Token: $token<br>";
echo "Profile Picture: $file_name<br>";
}
?>
PHP and MySQL are widely used together for building dynamic web applications. PHP acts as the backend scripting language, while MySQL is used to store and manage data efficiently. Establishing a connection between PHP and MySQL is crucial for performing database operations such as inserting, updating, retrieving, and deleting records.
PHP provides the mysqli_connect() function, which connects to the MySQL server and directly selects a database.
<?php
// Connect to MySQL and select the database
$conn = mysqli_connect("localhost", "root", "password", "test");
// Check if connection was successful
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully to the database";
?>
Explanation:
"localhost" → Server where MySQL is running (use localhost if running locally)."root" → MySQL username."password" → MySQL password (replace with your actual password)."test" → Name of the database to use.Once connected, you can run SQL queries like SELECT, INSERT, UPDATE, and DELETE.
<?php
$conn = mysqli_connect("localhost", "root", "password", "test");
// SQL query to insert data
$sql = "INSERT INTO users (name, email) VALUES ('John Smith', 'john@gmail.com')";
if (mysqli_query($conn, $sql)) {
echo "New record inserted successfully!";
} else {
echo "Error: " . mysqli_error($conn);
}
mysqli_close($conn); // Close the connection
?>
Explanation:
mysqli_query($conn, $sql) to execute the SQL statement.mysqli_error($conn) displays an error message if the query fails.mysqli_close($conn) ensures the connection is properly closed.<?php
$conn = mysqli_connect("localhost", "root", "password", "test");
// SQL query to retrieve records
$sql = "SELECT id, name, email FROM users";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
while ($row = mysqli_fetch_assoc($result)) {
echo "ID: " . $row["id"] . " - Name: " . $row["name"] . " - Email: " . $row["email"] . "<br>";
}
} else {
echo "No records found!";
}
mysqli_close($conn);
?>
<?php
$conn = mysqli_connect("localhost", "root", "password", "test");
$sql = "UPDATE users SET email='smith@gmail.com' WHERE name='John Smith'";
if (mysqli_query($conn, $sql)) {
echo "Record updated successfully!";
} else {
echo "Error updating record: " . mysqli_error($conn);
}
mysqli_close($conn);
?>
<?php
$conn = mysqli_connect("localhost", "root", "password", "test");
$sql = "DELETE FROM users WHERE name='John Smith'";
if (mysqli_query($conn, $sql)) {
echo "Record deleted successfully!";
} else {
echo "Error deleting record: " . mysqli_error($conn);
}
mysqli_close($conn);
?>
<?php
mysqli_close($conn);
?>
mysqli_connect() for modern applications instead of the deprecated mysql_connect().mysqli_close() after completing database operations.This guide provides a foundation for database-driven applications.