How many swimming records are there?
select count(*) from record
What about records that have results "Win"?
select count(*) from record where result = 'Win'
Show me the name of the swimmers who have any of those records.
select t1.name from swimmer as t1 join record as t2 on t1.id = t2.swimmer_id where result = 'Win'
Among those swimmers, who also have any records with results "Loss"?
select t1.name from swimmer as t1 join record as t2 on t1.id = t2.swimmer_id where result = 'Win' intersect select t1.name from swimmer as t1 join record as t2 on t1.id = t2.swimmer_id where result = 'Loss'