text: 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 Teachers (last_name VARCHAR); CREATE TABLE Teachers (last_name VARCHAR, teacher_id VARCHAR); CREATE TABLE Detention (teacher_id VARCHAR)
  ### Question:
  Find the last names of teachers who are not involved in any detention.
  ### Answer:
  SELECT last_name FROM Teachers EXCEPT SELECT T1.last_name FROM Teachers AS T1 JOIN Detention AS T2 ON T1.teacher_id = T2.teacher_id