Question: For each staff id, what is the description of the role that is involved with the most number of projects?
SQL: SELECT T1.role_description ,  T2.staff_id FROM Staff_Roles AS T1 JOIN Project_Staff AS T2 ON T1.role_code  =  T2.role_code JOIN Project_outcomes AS T3 ON T2.project_id  =  T3.project_id GROUP BY T2.staff_id ORDER BY count(*) DESC LIMIT 1