title: Calculate Mode() in Athena using group by
body: <p>I have a table 'A' with schema</p>
  <pre><code>subject, marks
  </code></pre>
  <p>Assume it has the following entries</p>
  <pre><code>(maths,90),(maths,90),(maths,80),(english,30),(english,30),(english,10)
  </code></pre>
  <p>I wish to calculate Mode() over the 'marks' column such that</p>
  <pre><code>(maths,90),(english,30) is the output
  </code></pre>
  <p>Can't find a way on the internet for the same for AWS Athena.
  Any help is appreciated !!</p>