$book = new Book();  //create a book object
$book->title = "Php is cool";  //assign a title to the book
$book->Save();  //this will insert the following record into the table
$book->title = "Php is very cool"; //modify the title of the book
$book->Save();  //this will update the record
$book = new Book();  //create a book object
$book->title = "Php is cool";  //assign a title to the book
$book->Save();  //this will insert the following record into the table
$book->title = "Php is very cool"; //modify the title of the book
if ($book->Save())
{
    echo "book successfully saved";
}
else
{
    echo "something bad happened, couldn't save";
}
$user= new User();  //create a user object
$user->GetUserList("username", "=", $_POST["username"]); //get a list of user with username supplied
$currentUser = $userList[ 0 ];  //assuming all usernames are unique, this should give you the correct user
if ($user->password == $_POST['password'])
{
    //log user in either by putting user id in the session or serializing the entire user
    $_SESSION['userId'] = $user->userId; // either put userid in session
    $_SESSION['user'] = serialize($user); //  or serialize user in session
}
else
{
    //user is not logged in
    echo "wrong username / password";
}
$user= new User();  //create a user object
$user->Get($_SESSION['userId']); //Get the logged in user
//If you serialized the user in the example above, you can simply unserialize it
$user->unserialize($_SESSION['user']);
$user->firstName = $_POST['firstName'];
$user->lastName = $_POST['lastName'];
$user->Save();  //this will update the user profile by updating the new firstname and lastname supplied