How can you ensure that form submissions in PHP do not result in duplicate values or unexpected characters being added to the data?

To ensure that form submissions in PHP do not result in duplicate values or unexpected characters being added to the data, you can implement validation and sanitization techniques. Validation ensures that the data meets certain criteria, such as being unique or not containing unwanted characters. Sanitization helps to clean the data by removing any potentially harmful characters or code. 

// Validate and sanitize form data
$name = isset($_POST['name']) ? filter_var($_POST['name'], FILTER_SANITIZE_STRING) : '';
$email = isset($_POST['email']) ? filter_var($_POST['email'], FILTER_VALIDATE_EMAIL) : '';

// Check for duplicate values
// Assuming $conn is your database connection
$stmt = $conn->prepare("SELECT COUNT(*) FROM users WHERE email = ?");
$stmt->bind_param("s", $email);
$stmt->execute();
$stmt->bind_result($count);
$stmt->fetch();
$stmt->close();

if ($count > 0) {
    // Handle duplicate email address
}

// Insert data into database
$stmt = $conn->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
$stmt->bind_param("ss", $name, $email);
$stmt->execute();
$stmt->close();

Keywords

PHP form submissions duplicate values unexpected characters data validation

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