MySQL брой делник/уикенд - част II

SELECT 
  fname, 
  MONTH(eventDate), 
  SUM(IF(WEEKDAY(eventDate) < 5,1,0)) AS WeekdayCount,
  SUM(IF(WEEKDAY(eventDate) >= 5,1,0)) AS WeekendCount
FROM eventcal AS e
LEFT JOIN users AS u ON e.primary = u.username
GROUP BY fname, MONTH(eventDate);

Искате да направите своите агрегирания (SUM в този случай) в SELECT и GROUP BY, както искате да се сумират (по fname, по MONTH).