What are the names and genders of staff who have held the title Sales Person, but never Clerical Staff?
return Staff ;return #1 held the  title Sales Person ;return #1 held the  title Clerical Staff ;return #2 besides  #3 ;return names of  #4 ;return genders of  #4 ;return #5 ,  #6
['select', 'filter', 'filter', 'discard', 'project', 'project', 'union']