CREATE TABLE Staff_Department_Assignments (staff_id VARCHAR(255), date_assigned_to INTEGER, job_title_code VARCHAR(255))
What is id of the staff who had a Staff Department Assignment earlier than any Clerical Staff?
    
SQL: SELECT staff_id FROM Staff_Department_Assignments WHERE date_assigned_to < (SELECT MAX(date_assigned_to) FROM Staff_Department_Assignments WHERE job_title_code = 'Clerical Staff')