SELECT friend FROM PersonFriend WHERE name =  'Zach' AND YEAR  =  (SELECT max(YEAR) FROM PersonFriend WHERE name =  'Zach')
Who is the friend of Zach with longest year relationship?
[Schema (values) (types)]: | network_2 |  Person : name (text) , age (text) , city (number) , gender (text) , job (text) | PersonFriend : name (text) , friend (text) , year (number);