+ $query->addSelect(['activities.created_at as last_activity_at'])
+ ->leftJoinSub(function (\Illuminate\Database\Query\Builder $query) {
+ $query->from('activities')->select('user_id')
+ ->selectRaw('max(created_at) as created_at')
+ ->groupBy('user_id');
+ }, 'activities', 'users.id', '=', 'activities.user_id');