title: How to check if value exists in each group (after group by)
body: <p>Assume I have a subscriptions table :</p>
  
  <pre><code>uid  | subscription_type 
  ------------------------  
  Alex | type1
  Alex | type2
  Alex | type3
  Alex | type4
  Ben  | type2
  Ben  | type3
  Ben  | type4
  </code></pre>
  
  <p>And want to select only the users that have more than 2 subscriptions but never subscribed with type 1 </p>
  
  <p>The expected result is selecting "Ben" only.</p>
  
  <p>I easy can found the users that have more than 2 subscribes using: </p>
  
  <pre><code>SELECT uid
  FROM subscribes
  GROUP BY uid
  HAVING COUNT(*) &gt; 2
  </code></pre>
  
  <p>But how to check if in a group some value never exists?</p>
  
  <p>Thanks for the help!</p>