The following snippet will connect to your MySQL database using the MySQL improved extension.
$mysqli = mysqli_connect('localhost', 'DATABASE_USERNAME', 'DATABASE_PASSWORD', 'DATABASE_NAME');
However, for the above connection code to work correctly, you must update the parameters to reflect your database credentials.
Check and output connection errors:
if (mysqli_connect_errno()) {
exit('Failed to connect to MySQL: ' . mysqli_connect_error());
}
Select database table and populate the results:
$result = $mysqli->query('SELECT * FROM students');
while ($row = $result->fetch_assoc()) {
echo $row['name'] . '';
}
Retrieve the number of rows:
$result->num_rows;
Insert a new record:
$mysqli->query('INSERT INTO students (name) VALUES ("Sagar")');
Retrieve the number of affected rows:
$mysqli->affected_rows;
Escape special characters in a string (which is vital if you're not using prepared statements):
$mysqli->real_escape_string($user_input_text);
Prepare statement (prevents SQL injection):
$name = 'Sagar';
$limit = 1;
// Prepare query
$stmt = $mysqli->prepare('SELECT age, address FROM students WHERE name = ? LIMIT ?');
// data types: i = integer, s = string, d = double, b = blog
$stmt->bind_param('si', $name, $limit);
// Execute query
$stmt->execute();
// Bind the result
$stmt->bind_result($age, address);
Close the query and database connection:
$stmt->close();
$mysqli->close();
The following snippet will escape HTML entities and quotes, which will prevent XSS attacks
htmlentities($text, ENT_QUOTES, 'UTF-8');
Decoding HTML entities:
html_entity_decode($text);
The following snippet will replace text in a string.
str_replace('Apple', 'Orange', 'My favourite fruit is an Apple.');
And to replace multiple words in a string, we can declare an array of strings:
str_replace(array('fruit', 'Apple'), array('Vegetable', 'Carrot'), 'My favourite fruit is an Apple.');
The following snippet will check if a string contains a specific word:
if (strpos('My name is Sagar.', Sagar) !== false) {
// String contains Sagar
}
With PHP >= 8, we can do:
if (str_contains('My name is Sagar.', Sagar)) {
// String contains Sagar
}
Inserting new items into an array:
$names = array();
array_push($names, 'Sagar', 'Akash');
We can also do:
$names = array();
$names[] = 'Sagar';
$names[] = 'Akash';
Remove item from an array:
unset($names['David']);
// or...
unset($names[0]);
Reindex the values after you have removed an item:
$names = array_values($names);
Reverse an array:
$reversed = array_reverse($names);
Merge two or more arrays:
$merged_array = array_merge($array1, $array2);
Return only the array keys:
$keys = array_keys(array('name' => 'Sagar', 'age' => 22));
Sort an array in ascending order:
sort($names);
Sort an array in reverse order:
rsort($names);
Check if an item exists in an array:
if (in_array('Sagar', $names)) {
// item exists
}
Check if key exists in an array:
if (array_key_exists('name', array('name' => 'Sagar', 'age' => 28))) {
// key exists
}
Count the number of items in an array:
count($names);
Convert comma-separated list to array:
$array = explode(',', 'sagar,aakash,akshay,khushi');
Retrieve a GET request parameter, which can be specified in the URL:
// index.php?name=sagar
echo $_GET['name'];
// index.php?name=sagar&surname=kumar
echo $_GET['surname'];
Check if request variable exists:
if (isset($_GET['name'])) {
// exists
}
Process HTML form data with PHP:
<form action="login.php" method="post">
Username: <input type="text" name="username"><br>
Password: <input type="password" name="password"><br>
<input type="submit">
</form>
login.php:
$user = $_POST['username'];
$pass = $_POST['password'];
echo 'Your username is ' . $user . ' and your password is ' . $pass . '.';
The following snippet will create a password hash using a one-way hashing algorithm
$hash = password_hash('your_password', PASSWORD_DEFAULT);
Verify your hashed passwords:
if (password_verify('your_password', $hash)) {
// hash is valid
}
In a nutshell, sessions act as cookies but are stored on the server as opposed to the client's computer. In addition, a unique ID is generated and stored as a cookie in the client's browser. It's used to associate the client with the session data.
The following snippet will create a new session.
session_start();
$_SESSION['name'] = 'Sagar';
Free all the session variables associated with the client from memory:
session_unset();
Destroy all the session variables associated with the client:
session_destroy();
The following snippet will redirect to a new page:
header('Location: http://example.com/newpage.php');
This snippet will get the IP address of the client:
if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
$ip = $_SERVER['HTTP_CLIENT_IP'];
} elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
$ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
} else {
$ip = $_SERVER['REMOTE_ADDR'];
}
echo $ip; // outputs the IP address to screen
The following snippet will get the contents of a file using cURL.
$url = 'http://example.com/file.json';
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_HEADER, false);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);
$result = curl_exec($curl);
curl_close($curl);
Using the PHP file_get_contents function:
$result = file_get_contents('file.json');
The following snippet will get the current date in string format.
$date = date('Y-m-d H:i:s');
echo $date;
Get the date from a timestamp:
$timestamp = 1641826797;
$date = date('Y-m-d H:i:s', $timestamp);
echo $date;
The following snippet will convert an PHP array to JSON.
$array = array('name' => 'Sagar', 'age' => 22);
$string = json_encode($array);
echo $string; // { "name" : "Sagar", "age" : 22 }
Parse an JSON file:
$string = file_get_contents('file.json');
$json = json_decode($string, true);
// $json['name'] etc...
The following snippet will send an e-mail.
$from = 'atechseva@yourwebsite.com';
$to = 'sagar@example.com';
$subject = 'Your Subject';
// Plain message
$message = 'Hello! How are you today?';
The following snippet will display the scripts execution time.
$time_start = microtime(true);
// Place your scripts here...
echo 'Total execution time in seconds: ' . (microtime(true) - $time_start);
The following snippet will get the full URL of your website (replace HTTP with HTTPS if using SSL).
$url = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
The following snippet will format a number.
$num = number_format(1000);
echo $num; // 1,000
Format number with decimals:
$num = number_format(1000.12, 2);
echo $num; // 1,000.12
The ZIP extension is required for this to work.
The following snippet will unzip an archive file on your server.
$zip = new ZipArchive;
$file = $zip->open('file.zip');
if ($file) {
$zip->extractTo('/extract_path/');
$zip->close();
echo 'Archive extracted successfully!';
}
The following snippet will detect if the client is using a mobile device.
if (preg_match("/(android|avantgo|blackberry|bolt|boost|cricket|docomo|fone|hiptop|mini|mobi|palm|phone|pie|tablet|up\.browser|up\.link|webos|wos)/i", $_SERVER["HTTP_USER_AGENT"])) {
// Is mobile...
}
The following snippet will check if a file exists.
if (file_exists('example.png')) {
// File exists
}
These snippets are useful if you develop PHP applications regularly or if you're a beginner programmer looking for a particular snippet. Keep the page bookmarked for future reference.
Enjoy coding!
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