In a multi-user environment, what considerations should be taken into account when displaying form data after submission in PHP?

When displaying form data after submission in a multi-user environment, it is important to ensure that the data being displayed belongs to the correct user. This can be achieved by storing the user's information in a session variable upon login and checking this information against the submitted form data before displaying it. 

// Start the session
session_start();

// Check if the user is logged in
if(isset($_SESSION['user_id'])){
    // Get the user's ID from the session
    $user_id = $_SESSION['user_id'];

    // Retrieve the form data from the database based on the user's ID
    $query = "SELECT * FROM form_data WHERE user_id = $user_id";
    $result = mysqli_query($connection, $query);

    // Display the form data
    while($row = mysqli_fetch_assoc($result)){
        echo "Name: " . $row['name'] . "<br>";
        echo "Email: " . $row['email'] . "<br>";
        // Add more fields as needed
    }
} else {
    echo "You are not logged in.";
}

Keywords

security session management data validation SQL injection cross-site scripting

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