SELECT Event.id, sum(Attendees.total_raised), sum(Attendees.total_hours)
 FROM Events JOIN Attendees ON Events.id = Attendees.event_id
 GROUP BY Event.id

$q = DB::table('events')
       ->join('attendees', 'events.id', '=', 'attendees.event_id')
       ->sum('total_raised')
       ->sum('total_hours');

...

->get(
  array(
    'events.id',
    DB::raw('SUM(attendees.total_raised)'),
    DB::raw('SUM(attendees.total_hours)')
  )
);

$query = DB::table('events')->join('attendees', 'events.id', '=', 'attendees.event_id');

$raised = $query->sum( 'total_raised' );

$hours = $query->sum( 'total_hours' );

$result = DB::table('events')->join('attendees', 'events.id', '=', 'attendees.event_id')
    ->get( array(
        DB::raw( 'SUM(attendees.total_raised) AS raised' ),
        DB::raw( 'SUM(attendees.total_hours) AS hours' ),
    ));

$result = self::select("*", DB::raw('SUM(auction_amount) as total_auction_amount') , DB::raw('SUM(commission_amount) as total_commission_amount'),
            DB::raw('SUM(deposit_amount) as total_deposit_amount'))
            ->groupBy('cp_user_id')
            ->get()
            ->toArray();

$result = self::select("*", DB::raw('SUM(auction_amount) as total_auction_amount') , DB::raw('SUM(Attendees.total_raised) as total_raised'),
            DB::raw('SUM(Attendees.total_hours) as total_hours'))
            ->with('Attendees')
            ->groupBy('id')
            ->get()
            ->toArray();