/*6. Write a query to list all the salesmen, and indicate those who do not have customers in their cities, as well as whose 
who do.*/
SELECT salesman.salesman_id, name, cust_name, commission  
FROM salesman, customer  
WHERE salesman.city = customer.city  
UNION  
SELECT salesman_id, name, 'NO MATCH', commission  
FROM salesman  
WHERE NOT city = ANY  
    (SELECT city  
        FROM customer)  
ORDER BY 2 DESC;