Cakephp Save Update Data From Old Data Value + New Value

I don't know the keyword to search with my problem. How to save update data of a field that already exist a value and I want to update it with additional value. Here is an example

Solution 1:

updateAll will work

$this->User->updateAll(
       array('credit' => "credit + $newCredit"),
       array('id' => $userId)
    );

Solution 2:

Try this one:

$userData = array(
      'id' => $userId,
      'credit' => 'credit +'.$newCredit// old credit value + new credit value
);
$this->User->save($userData);

Or this:

$newCredit = 566;
$this->User->read(null, $userId);
$this->User->set('credit',$this->User->field('credit') + $newCredit);
$this->User->save();