How many people are friends with Dan?
select count(*) from personfriend where friend = 'Dan'
How about for Alice?
select count(*) from personfriend where friend = 'Alice'
Show the name and age of poeple who are friends with either.
select distinct t1.name, t1.age from person as t1 join personfriend as t2 on t1.name = t2.name where t2.friend = 'Dan' or t2.friend = 'Alice'