title: DynamoDB - Get Item by Global Secondary Index
body: <p>I have an existing table which has 10 fields. Fields are like this:</p>
  <blockquote>
  <p>AuthID, UserID, Age, Job, .etc</p>
  </blockquote>
  <p>The table stores data of my users. &quot;AuthID&quot; is primary key and &quot;UserID&quot; is a Global Secondary Index.</p>
  <p>When I get item by AuthID, everything is fine. But I can't get item by UserID. I tried GetItem, Query and Scan methods but I failed in all three method.</p>
  <p>I need to be able to get data with these 3 methods I wrote below :</p>
  <pre><code>1 - Get user data by AuthID (It's already works fine)
  2 - Get user data by UserID
  3 - Get user data by AuthID and UserID both
  </code></pre>
  <p>AuthID and UserID is unique. Can someone point me right way as to what to do?</p>