What is the name that only has one friend pairing?
select name from personfriend group by name having count ( * ) = 1
How many times does Alice show up in the friend column?
select count ( * ) from personfriend where friend = 'Alice'
How many times does Bob show up in the friend column?
select count ( * ) from personfriend where friend = 'Bob'
who is Bob's friend?
select friend from personfriend where name = 'Bob'
who is Zach's friend?
select friend from personfriend where name = 'Zach'
How many names are in the name column?
select count ( distinct name ) from personfriend
how many names are in the friends column?
select count ( distinct friend ) from personfriend