Database: tracking_grants_for_research

Question: What are the staff roles of the staff who starts working after 2003-04-19 15:06:20 and ends working before 2016-03-15 00:33:18?
SQL: SELECT role_code FROM Project_Staff WHERE date_from  >  '2003-04-19 15:06:20' AND date_to  <  '2016-03-15 00:33:18'