select student_id, sum(contest_id) from contestInfo ;

select student_id, sum(contest_id) from contestInfo group by student_id;

select student_id, count(contest_id) from contestInfo;

select student_id, count(contest_id) from contestInfo group by student_id;

select student_id, max(contest_id) from contestInfo;

select student_id, max(contest_id) from contestInfo group by student_id;