title: Firebase query showing wrong data
body: <p>I have user profiles stored in Firebase with a key "Pricing" and some value saved as integer. I also have profiles that DO NOT have that key.</p>
  
  <p>I execute:</p>
  
  <pre><code>usersReference = Database.database().reference(fromURL: "https://someRef")
      .child("users")
      .queryOrdered(byChild: "Pricing")
      .queryEnding(atValue: pricingToSearch)
      .observe(...)
  </code></pre>
  
  <p>However, the query result is always showing me also the profiles without that key. How can I exclude them from the search?</p>