Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE CUSTOMER (LastName VARCHAR); CREATE TABLE CUSTOMER (LastName VARCHAR, CustomerId VARCHAR); CREATE TABLE Invoice (CustomerId VARCHAR, total INTEGER)
### Question:
Find all the customer last names that do not have invoice totals larger than 20.
### Answer:
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