title: How to group by date, accounting for timezones and DST?
body: <p>I have a bunch of events stored in my database. Each event has a start time, stored as <code>DATETIME</code> in UTC. Each user can choose his/her own timezone.</p>
  
  <p>I want to display a calendar which just shows the number of events on each day of the month. I can't <code>GROUP BY DATE(start_dt)</code> because the user's day does not [necessarily] start at 00:00:00 UTC. Moreover, the user's timezone may have a DST switch in the middle of the month.</p>
  
  <p>Is my only option then to fetch every single event for the given month and then group and count them with my server-side language?</p>