What steps can be taken to ensure that PHP code properly handles form submissions and database queries to prevent issues like incorrect data display after page reloads?

To ensure that PHP code properly handles form submissions and database queries to prevent issues like incorrect data display after page reloads, it is important to use techniques like input validation, sanitization, and prepared statements for database queries. Additionally, utilizing sessions or cookies to store and retrieve form data can help maintain the integrity of the data across page reloads. 

// Example of handling form submission and database query with input validation and prepared statements

// Validate form input
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = $_POST['name'];
    $email = $_POST['email'];
    
    // Sanitize input
    $name = filter_var($name, FILTER_SANITIZE_STRING);
    $email = filter_var($email, FILTER_SANITIZE_EMAIL);
    
    // Prepare and execute database query
    $stmt = $pdo->prepare("INSERT INTO users (name, email) VALUES (:name, :email)");
    $stmt->bindParam(':name', $name);
    $stmt->bindParam(':email', $email);
    $stmt->execute();
    
    // Redirect to prevent form resubmission
    header("Location: success.php");
    exit();
}

Keywords

form submissions database queries data display page reloads error prevention

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