Find the name and gender of the staff who has been assigned the job of Sales Person but never Clerical Staff.
create table staff (staff_name varchar, staff_gender varchar, staff_id varchar, PRIMARY KEY (staff_name)); create table staff_department_assignments (staff_id varchar, job_title_code varchar, PRIMARY KEY (staff_id))
select t1.staff_name, t1.staff_gender from staff as t1 join staff_department_assignments as t2 on t1.staff_id = t2.staff_id where t2.job_title_code = "sales person" except select t1.staff_name, t1.staff_gender from staff as t1 join staff_department_assignments as t2 on t1.staff_id = t2.staff_id where t2.job_title_code = "clerical staff"