select CUSTOMERS.CUSTOMERNAME,
       CUSTOMERS.CUSTOMERNUMBER,CLASSICMODELS.CUSTOMERS.CREDITLIMIT,
       ordersums.OrderTotals,
       paymentsums.PaidTotals
from CUSTOMERS, 
( select ORDERS.CUSTOMERNUMBER, sum(ORDERDETAILS.QUANTITYORDERED * ORDERDETAILS.PRICEEACH) as OrderTotals 
from ORDERS, ORDERDETAILS where ORDERDETAILS.ORDERNUMBER = ORDERS.ORDERNUMBER
group by ORDERS.CUSTOMERNUMBER) ordersums,
( select CUSTOMERS.CUSTOMERNUMBER, sum(PAYMENTS.AMOUNT) as PaidTotals 
from CUSTOMERS, PAYMENTS where PAYMENTS.CUSTOMERNUMBER = CUSTOMERS.CUSTOMERNUMBER
group by CUSTOMERS.CUSTOMERNUMBER) paymentsums

where CUSTOMERS.CUSTOMERNUMBER = ordersums.CUSTOMERNUMBER
and CUSTOMERS.CUSTOMERNUMBER = paymentsums.CUSTOMERNUMBER