MYSQL SUM 2 Table ทำยังไงครับ Error แล้ว Error อีก T_T

SELECT A_ID, A_TITLE, ( A_PRICE + COALESCE( SUM( B_PRICE ) , 0 ) )SUM_AB
FROM `a` LEFT JOIN B ON A_ID = B_AID GROUP BY A_ID

SELECT booking_id,booking_location,booking_station,booking_target,booking_detail,booking_datetime,booking_start,booking_strdate,booking_enddate,booking_member,
	( booking_pay + COALESCE( SUM(surcharge_price) , 0 ) )SUM_AB
FROM booking left join booking_surcharge on booking_id = surcharge_booking_id 
left join user on booking.booking_member = user.userid 
left join locations on booking_location=location_id 
GROUP BY booking_id 

$strSQL2 = "SELECT
booking_id,
booking_location,
booking_station,
booking_target,
booking_detail,
booking_datetime,
booking_start,
booking_strdate,
booking_enddate,
booking_member,
user.*,
locations.*,
booking_surcharge.*,
( booking_pay + COALESCE( SUM(surcharge_price) , 0 ) ) SUM_AB
FROM booking
left join booking_surcharge on booking.booking_id = booking_surcharge.surcharge_booking_id
left join user on booking.booking_member = user.userid
left join locations on booking.booking_location=locations.location_id
GROUP BY booking.booking_id ";		
$sumQUERY = mysql_query($strSQL2);
$sum = mysql_fetch_array($sumQUERY);
echo $sum['SUM_AB'];