SELECT first_name FROM Staff EXCEPT SELECT T2.first_name FROM Lessons AS T1 JOIN Staff AS T2 ON T1.staff_id  =  T2.staff_id
What is the first name of all employees who do not give any lessons?
SELECT first_name FROM Staff EXCEPT SELECT T2.first_name FROM Lessons AS T1 JOIN Staff AS T2 ON T1.staff_id = T2.staff_id
select first_name from staff except select t2 . first_name from lessons as t1 join staff as t2 on t1 . staff_id = t2 . staff_id
What is the first name of all employees who do not give any lessons ?