Question: Show the staff ids of the project staff involved in the most number of project outcomes?
SQL: SELECT 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