How to add new record in Database using PHP and mysqli

$conn = new mysqli("localhost","root","password","dbname");
if(! $conn ) {
   die('Could not connect to the database ');
}
$userName = "russel";
$userEmail = "[email protected]";
$timestamp = date('Y-m-d H:i:s');

$insertData = "INSERT INTO users (username, email, timestamp) VALUES ('$userName', '$userEmail', '$timestamp')";

if (mysqli_query($conn, $insertData)) {  
	echo "Record added successfully";
} 
else {
	echo "Error adding record: " . mysqli_error($conn);
}