SELECT Cust_ID, total, Commercial.COMPANY_NAME, Commercial.VAT_Number FROM
(
SELECT Customer_ID AS Cust_ID, SUM(Payment_Amount) total FROM
(
SELECT * FROM Order_Table, Pay_Link WHERE Order_Table.Order_ID = Pay_Link.Order_ID
)
GROUP BY Customer_ID
ORDER BY total DESC
), Commercial
INNER JOIN Customer
ON Customer.Customer_ID = Commercial.Customer_ID
WHERE ROWNUM <= (SELECT COUNT (*) FROM Commercial) / 4 AND cust_id = Commercial.Customer_ID;