$monthDurations = $user->times()
->whereYear('start_day', 2019)
->select(
\DB::raw('SUM(TIME_TO_SEC(duration)) as `month_duration_in_seconds`'),
\DB::raw('DATE_FORMAT(start_day, "%Y-%m") as `year_month`'),
'category',
'user_id'
)
->groupBy(\DB::raw('DATE_FORMAT(start_day, "%Y-%m")'), 'category', 'user_id')
->get();