MySQL Query GROUP BY day / month / year

GROUP BY YEAR(record_date), MONTH(record_date)

Check out the date and time functions in MySQL.

GROUP BY DATE_FORMAT(record_date, '%Y%m')

---

Note (primarily, to potential downvoters). Presently, this may not be as efficient as other suggestions. Still, I leave it as an alternative, and a one, too, that can serve in seeing how faster other solutions are. (For you can't really tell fast from slow until you see the difference.) Also, as time goes on, changes could be made to MySQL's engine with regard to optimisation so as to make this solution, at some (perhaps, not so distant) point in future, to become quite comparable in efficiency with most others.