facebook DS面试题

请问下，
Given data on Facebook members friending/defriending each other on Facebook, find out whether a given pair of members are currently friends.

可以用sql做么？
如何解呢

order by friending/defriending date, if max date is friending, then they are current friends.

Solution:
http://developer.51cto.com/art/201301/375661.htm

I have prepared this question, but Facebook do not give me opportunity to answer.
my preparation:
http://www.1point3acres.com/bbs/thread-200022-4-1.html