Table schema:
CREATE TABLE PersonFriend (name VARCHAR, friend VARCHAR); CREATE TABLE Person (age INTEGER, name VARCHAR)

Question: Which person whose friends have the oldest average age?
SQL: SELECT T2.name, AVG(T1.age) FROM Person AS T1 JOIN PersonFriend AS T2 ON T1.name = T2.friend GROUP BY T2.name ORDER BY AVG(T1.age) DESC LIMIT 1