title: How to count distinctly with conditions?
body: <p>I have a query something like this, and it gives how many shops we have for each product and cluster.</p>
  <pre><code>SELECT product,
           cluster,
           count(distinct shop_id) AS shops
  FROM a
  WHERE site = 1 
  GROUP BY  1, 2 
  </code></pre>
  <p>However, I'd like to see whether there are other shops with the same cluster for each product. So, if there are other shops (&gt; 1) YES, if not (&lt;= 1) NO, and my desired output would be like this:</p>
  <pre><code>    product | other_shops
      X            Yes
      Y            No
  </code></pre>
  <p>How can I do this?</p>