title: mysql group by show count 0 not sure if I can left join here
body: <p>I have this query and I want to return a row when the count is 0</p>
  
  <pre><code>SELECT count(day) as count, day
  FROM `table`
  GROUP BY `day`
  </code></pre>
  
  <p>Other stackoverflow answers say that I need to do a left join.<br>
  But I don't know how to do it in this scenario.</p>