What are their genders? | Would you like their names and their genders? | Yes.
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"
Names and genders of staff who are 'Sales Person' but not 'Clerical Staff'; staff_name refers to names of staff, staff_gender refers to genders of staff; EXCEPT is used to subtract the second query result from the first.