title: Retrieving row count and returning 0 when no rows
body: <p>I've written a query to retrieve how many website signups I've had every day:</p>
  
  <pre><code>SELECT created, COUNT(id)
  FROM signups
  GROUP BY created
  ORDER BY created desc
  </code></pre>
  
  <p>However, this only retrieves rows for days where people have actually signed up. If nobody has signed up in a day, I would like to return 0 for that day. Is there a way to do this using SQL or will I have to parse through the results using PHP?</p>