What are the names of all users?
select name from useracct
How many reviews were given by each user?
select t1.name, count(*) from useracct as t1 join review as t2 on t1.u_id = t2.u_id group by t2.u_id
Order by the number of reviews given, from the greatest to the least.
select t1.name, count(*) from useracct as t1 join review as t2 on t1.u_id = t2.u_id group by t2.u_id order by count(*) desc
Who gave the most reviews?
select t1.name from useracct as t1 join review as t2 on t1.u_id = t2.u_id group by t2.u_id order by count(*) desc limit 1