What's wrong with this statement? An error is occurring, it is not reading the second line
(($var = array('tab.order' => 'tab.order+1');))
$db->update('tab', $form->getValues(), array('id =?' => $id));
$var = array('tab.order' => 'tab.order+1');
$var2 = array('tab.order >= ' . $form->getValue('order'));
$db->update('tab', $var, $var2);
$vardoes not exist, does not have the value you expect, etc?