title: PHP MongoDB update multiple documents using $in/$or
body: <p>I'm having trouble figuring out how to construct an update query in PHP that will update document IDs X,Y, and Z. Does anyone have experience with this?</p>
  
  <pre><code>$ids[] = array(
    new MongoId('4eaaf929498fe2c80300000c'),
    new MongoId('4eaaff24498fe2ba0900001f')
  ); 
  $collection-&gt;update(
    array('_id' =&gt; array('$in' =&gt; $ids)),
    array('$set' =&gt; array("title"=&gt;"test")),
    array("upsert" =&gt; true)
  );
  </code></pre>