What resources or existing scripts can be recommended for creating a user online counter in PHP?

To create a user online counter in PHP, you can use a combination of session variables and a database to track and display the number of online users. You can increment the counter when a user logs in and decrement it when they log out or their session expires. 

<?php
session_start();

// Establish connection to the database
$connection = mysqli_connect("localhost", "username", "password", "database");

// Check if user is logged in and increment online counter
if(isset($_SESSION['user_id'])) {
    $user_id = $_SESSION['user_id'];
    $query = "UPDATE online_users SET count = count + 1 WHERE user_id = $user_id";
    mysqli_query($connection, $query);
}

// Retrieve online user count
$query = "SELECT count(*) as online_users FROM online_users";
$result = mysqli_query($connection, $query);
$row = mysqli_fetch_assoc($result);
$online_users = $row['online_users'];

// Display online user count
echo "Users online: " . $online_users;

// Decrement online counter when user logs out or session expires
// This code should be placed in the logout script or session expiration handling
// $query = "UPDATE online_users SET count = count - 1 WHERE user_id = $user_id";
// mysqli_query($connection, $query);

mysqli_close($connection);
?>

Keywords

PHP user online counter resources existing scripts recommendations

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