What are common mistakes to avoid when handling form submissions in PHP?

Common mistakes to avoid when handling form submissions in PHP include not validating user input, not sanitizing data before using it in a database query, and not protecting against SQL injection attacks. To solve these issues, always validate user input to ensure it meets the expected format, sanitize data to prevent malicious code injection, and use prepared statements or parameterized queries to protect against SQL injection attacks. 

// Example of handling form submission with validation, sanitization, and protection against SQL injection

// Validate user input
$name = isset($_POST['name']) ? $_POST['name'] : '';
$email = isset($_POST['email']) ? $_POST['email'] : '';

if(empty($name) || empty($email)){
    // Handle validation error
    echo "Name and email are required";
    exit;
}

// Sanitize data
$name = filter_var($name, FILTER_SANITIZE_STRING);
$email = filter_var($email, FILTER_SANITIZE_EMAIL);

// Protect against SQL injection
$stmt = $pdo->prepare("INSERT INTO users (name, email) VALUES (:name, :email)");
$stmt->bindParam(':name', $name);
$stmt->bindParam(':email', $email);
$stmt->execute();

// Success message
echo "Form submitted successfully";

Keywords

SQL injection cross-site scripting validation sanitization error handling

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