Are there best practices for implementing IP checks in PHP to prevent duplicate entries?

To prevent duplicate entries based on IP checks in PHP, one best practice is to store the IP addresses of users who have already submitted data in a database. When a new entry is submitted, check if the IP address of the user matches any existing entries before allowing the submission to proceed. 

// Connect to database
$pdo = new PDO('mysql:host=localhost;dbname=your_database', 'username', 'password');

// Get user's IP address
$user_ip = $_SERVER['REMOTE_ADDR'];

// Check if IP address already exists in database
$stmt = $pdo->prepare("SELECT * FROM submissions WHERE ip_address = :ip");
$stmt->bindParam(':ip', $user_ip);
$stmt->execute();

if ($stmt->rowCount() > 0) {
    echo "Duplicate entry detected. Please try again later.";
    // Additional logic to handle duplicate entry
} else {
    // Proceed with inserting new entry into database
    $stmt = $pdo->prepare("INSERT INTO submissions (ip_address, data) VALUES (:ip, :data)");
    $stmt->bindParam(':ip', $user_ip);
    $stmt->bindParam(':data', $your_data);
    $stmt->execute();
    echo "Entry submitted successfully.";
}

Keywords

IP address duplicate entries PHP implementation prevention

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