SELECT LastName FROM CUSTOMER EXCEPT SELECT T1.LastName FROM CUSTOMER AS T1 JOIN Invoice AS T2 ON T1.CustomerId  =  T2.CustomerId WHERE T2.total  >  20
What are the last names of customers without invoice totals exceeding 20?
SELECT LastName FROM CUSTOMER EXCEPT SELECT T1.LastName FROM CUSTOMER AS T1 JOIN Invoice AS T2 ON T1.CustomerId = T2.CustomerId WHERE T2.total > 20
select lastname from customer except select t1 . lastname from customer as t1 join invoice as t2 on t1 . customerid = t2 . customerid where t2 . total > value
What are the last names of customers without invoice totals exceeding 20 ?