How i can use entity_metadata_wrapper for new database entry and update data in Drupal 7 How i can use entity_metadata_wrapper for database entry and update data in Drupal 7 

I am using below code to save entry in database but not finding logic to update existing entry

    $node = new stdClass();
    $node-&gt;type = "event";
    $node-&gt;uid = $user_id;          
    $entity_wrapper = entity_metadata_wrapper('node',$node);
    $entity_wrapper-&gt;title-&gt;set($row-&gt;title);
    $entity_wrapper-&gt;body-&gt;set($row-&gt;description);
    $entity_wrapper-&gt;status-&gt;set(0); 
    $entity_wrapper-&gt;promote-&gt;set(0);
    $entity_wrapper-&gt;comment-&gt;set(0);
    $entity_wrapper-&gt;field_eventbrite-&gt;set($row-&gt;eid);          
    $entity_wrapper-&gt;field_venue-&gt;set($row-&gt;name);
    $entity_wrapper-&gt;field_eventbrite_city-&gt;set($row-&gt;city);
    $entity_wrapper-&gt;field_privacy-&gt;set($row-&gt;privacy);
    $entity_wrapper-&gt;field_repeats-&gt;set($row-&gt;repeats);
    $entity_wrapper-&gt;field_date_period-&gt;set(array(
        'value' =&gt; str_replace(' ', 'T',$row-&gt;start_date),
        'value2' =&gt; str_replace(' ', 'T', $row-&gt;end_date),
    ));
    $entity_wrapper-&gt;field_eventbrite_url-&gt;set(array(
        'url' =&gt; $row-&gt;url,
    ));
    $entity_wrapper-&gt;save();


Please help. Please let me know if require more information is needed.Thanks..
Its simple

// $nid - nid of node you want to udate
$node = node_load($nid);
$entity_wrapper = entity_metadata_wrapper('node',$node);
...
$entity_wrapper-&gt;field_eventbrite-&gt;set($row-&gt;eid);          
$entity_wrapper-&gt;field_venue-&gt;set($row-&gt;name);
$entity_wrapper-&gt;save();