title: How to query based on multiple conditions in Firebase?
body: <p>I have this following structure:</p>
  
  <pre><code>{
    "users" : {
      "123" : {
        "activities" : {
          "horse" : "horse",
          "bike" : "bike"
        },
        "age" : 21
      },
      "124" : {
        "activities" : {
          "bike" : "bike"
        },
        "age" : 30
    }
  }
  </code></pre>
  
  <p>I am trying to do something similar to: </p>
  
  <p><code>SELECT * FROM users WHERE (activities = 'horse' OR activities = 'bike') AND age &gt;= 21</code></p>
  
  <p>Can I please get some pointers on this? If I didn't structured the data properly, can I also get some tips there?</p>
  
  <p>edit: <a href="http://jsfiddle.net/patrioticcow/uvn6y1dg/3/" rel="nofollow">jsfiddle</a></p>