SELECT T1.LastName FROM CUSTOMER AS T1 JOIN EMPLOYEE AS T2 ON T1.SupportRepId  =  T2.EmployeeId GROUP BY T1.SupportRepId HAVING COUNT(*)  <=  20
Please show the employee last names that serves no more than 20 customers.
SELECT T1.LastName FROM CUSTOMER AS T1 JOIN EMPLOYEE AS T2 ON T1.SupportRepId = T2.EmployeeId GROUP BY T1.SupportRepId HAVING COUNT ( * ) < = 20
select t1 . lastname from customer as t1 join employee as t2 on t1 . supportrepid = t2 . employeeid group by t1 . supportrepid having count ( * ) < = value
Please show the employee last names that serves no more than 20 customers .