What are common mistakes that PHP developers make when handling form submissions that lead to data persistence issues?

One common mistake is not properly sanitizing and validating user input before processing form submissions, which can lead to data persistence issues such as SQL injection attacks or incorrect data being saved to the database. To solve this issue, always use functions like htmlspecialchars() and mysqli_real_escape_string() to sanitize user input and validate it against expected formats before saving it to the database. 

// Sanitize and validate user input before saving to the database
$name = htmlspecialchars($_POST['name']);
$email = htmlspecialchars($_POST['email']);

// Validate email format
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    echo "Invalid email format";
    exit;
}

// Save data to the database
// Example using mysqli
$conn = new mysqli($servername, $username, $password, $dbname);
$stmt = $conn->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
$stmt->bind_param("ss", $name, $email);
$stmt->execute();
$stmt->close();
$conn->close();

Keywords

SQL injection XSS attacks form validation CSRF protection session management

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