title: Get result where exist on date X and not exist on day Y
body: <p>I have a table where I store some info about events. My table have columns: id, created_at(which is date field), key(which is varchar255), quantity(which is integer) and event(which is varchar255). I'm making query to take all keys which exists on date X (for example 2022-09-05) and NOT exists on date Y (example 2022-09-06). The table has no relation with other tables.</p>
  <p>The query that I tried is:</p>
  <pre><code>SELECT s.key
  FROM stats s
  WHERE created_at = '2022-09-05'
  AND NOT EXISTS(
      SELECT *
      FROM stats s
      WHERE s.created_at = '2022-09-06'
      )
  GROUP BY s.key
  ;
  </code></pre>
  <p>The problem is this returns me 0 result, but I expect at least 1.</p>