Grab unique vintages for accounts stocks.

stock.rb

def stocked_countries
  joins(<<END
INNER JOIN wine_instances wi ON wi.id = stocks.wine_instance_id 
INNER JOIN wines w ON w.id = wine_instances.wine_id 
INNER JOIN countries c c.id = w.country_id
END).select("DISTINCT(c.name) AS country_name").order("country_name").map { |v| v.country_name }
end