What are the best practices for preventing users from being double-linked in a web application using PHP?

To prevent users from being double-linked in a web application using PHP, you can utilize session variables to track whether a user has already performed a certain action. By setting a session variable after the action has been taken, you can then check for the presence of this variable before allowing the action to be performed again. 

session_start();

if(isset($_SESSION['action_taken'])){
    // Redirect or display an error message to prevent double-linking
    exit;
}

// Perform the action here

$_SESSION['action_taken'] = true;

Keywords

validation uniqueness database SQL injection session management

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