query: SELECT role_code FROM Project_Staff WHERE date_from  >  '2003-04-19 15:06:20' AND date_to  <  '2016-03-15 00:33:18'
question: Who what being a staff role them a staff
query_toks: SELECT role_code FROM Project_Staff WHERE date_from > '2003-04-19 15:06:20 ' AND date_to < '2016-03-15 00:33:18 '
query_toks_no_value: select role_code from project_staff where date_from > value and date_to < value
question_toks: Who what being a staff role them a staff