select c.cust_name, Orn.total_price
from 
    (
        select  a.order_num, SUM(a.item_price * a.quantity) as total_price
        from OrderItems a
        group by a.order_num
        having total_price >= 1000
        order by a.order_num
    ) Orn, Orders b, Customers c
 where Orn.order_num = b.order_num and b.cust_id = c.cust_id