title: Android Firebase Database query select with condition
body: <p>I want to <code>SELECT * FROM products WHERE 'birthday' = true;</code>
  But can I do the same with Firebase Database ?</p>
  
  <p>I have tried</p>
  
  <pre><code>DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
  ref. child("products").orderByChild("birthday").equalTo(true).addChildEventListener ........
  </code></pre>
  
  <p><a href="http://m.imgur.com/gallery/IiF6dU9" rel="nofollow noreferrer">Firebase Database image</a></p>
  
  <p>But it doesn't work.Please help. 
  f my data structure is bad, please also advise how to create a better structure.</p>