What is the name of the swimmer who has the greatest number of records?
select t1.name from swimmer as t1 join record as t2 on t1.id = t2.swimmer_id group by t2.swimmer_id order by count ( * ) desc limit 1
What about the least number of records?
select t1.name from swimmer as t1 join record as t2 on t1.id = t2.swimmer_id group by t2.swimmer_id order by count ( * ) asc limit 1
What are the nationalities of swimmers "Grant Hackett" and "Craig Stevens"?
select nationality from swimmer where name = "Grant Hackett" or name = "Craig Stevens"