/*Write a SQL statement to make a list for the salesmen who either work for one or more customers or yet to join any of the
 customer. The customer, may have placed, either one or more orders on or above order amount 2000 and must have a grade, or
  he may not have placed any order to the associated supplier.*/
SELECT a.cust_name,a.city,a.grade,   
b.name AS "Salesman",   
c.ord_no, c.ord_date, c.purch_amt   
FROM customer a   
RIGHT OUTER JOIN salesman b   
ON b.salesman_id=a.salesman_id   
RIGHT OUTER JOIN orders c   
ON c.customer_id=a.customer_id   
WHERE c.purch_amt>=2000   
AND a.grade IS NOT NULL;