Who are all the reviewers?
select name from reviewer
What is their highest rating?
select t2.name, max(t1.stars) from rating as t1 join reviewer as t2 on t1.rid = t2.rid group by t2.name
What is their lowest rating?
select t2.name, min(t1.stars) from rating as t1 join reviewer as t2 on t1.rid = t2.rid group by t2.name
What about their average rating?
select t2.name, avg(t1.stars) from rating as t1 join reviewer as t2 on t1.rid = t2.rid group by t2.name