title: Yii2 find query using mongodb
body: <p>I want to use query something like :</p>
  
  <pre><code>Select * from company where id is not null order by id desc
  </code></pre>
  
  <p>I am using YII2 framework with mongodb:</p>
  
  <pre><code>$company = Company::find()-&gt;where(['id' =&gt; null])-&gt;all();
  </code></pre>
  
  <p>The above query works fine for me but i want to use NOT NULL condition with order by. How can i do this ?</p>