CREATE TABLE cust_orders
(custid int,
 supid int,
 orderid int,
 orderdate datetime)

 INSERT INTO cust_orders
 VALUES (1,1,2,getdate() + 1)
 INSERT INTO cust_orders
 VALUES (1,2,3,getdate() + 2)
 INSERT INTO cust_orders
 VALUES (1,3,4,getdate() + 3)
 INSERT INTO cust_orders
 VALUES (1,4,5,getdate() + 4)
 INSERT INTO cust_orders
 VALUES (1,5,6,getdate() + 5)
 INSERT INTO cust_orders
 VALUES (1,6,7,getdate() + 6)
INSERT INTO cust_orders
 VALUES (2,1,2,getdate() + 1)
 INSERT INTO cust_orders
 VALUES (2,2,3,getdate() + 2)
 INSERT INTO cust_orders
 VALUES (2,3,4,getdate() + 3)
 INSERT INTO cust_orders
 VALUES (2,4,5,getdate() + 4)
 INSERT INTO cust_orders
 VALUES (2,5,6,getdate() + 5)
 INSERT INTO cust_orders
 VALUES (2,6,7,getdate() + 6)

 SELECT TabA.custid , TabA.supid , TabA.orderid,  TabA.orderdate
 FROM cust_orders TabA
 JOIN
        (SELECT MAX(orderdate) AS orderdate , custid
        FROM cust_orders
        GROUP BY custid) as tabB
 ON TabA.custid = tabB.custid AND TabA.orderdate = tabB.orderDate