NoMethodError: undefined method `more_results' for #<Mysql>

I am trying to create rake task to import data from my old php application.But I can not connect to mysql database properly, when I run Old::User.all on rails console ,I get this error :

NoMethodError: undefined method `more_results' for #<Mysql>

        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/connection_adapters/mysql_adapter.rb:623:in `select'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all'
        from /Library/Ruby/Gems/1.8/gems/activer开发者_JAVA百科ecord-3.0.3/lib/active_record/connection_adapters/abstract/query_cache.rb:56:in `select_all'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/base.rb:467:in `find_by_sql'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/relation.rb:64:in `to_a'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/relation/finder_methods.rb:143:in `all'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/base.rb:439:in `__send__'
        from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/base.rb:439:in `all'
        from (irb):1

Model class Old/user.rb

class Old::User < ActiveRecord::Base
  establish_connection "old_database"

  # Because table name is lowercase
  def self.table_name() 
    "user"
  end
end

database.yml

old_database:
  adapter: mysql
  database: old_database
  username: root
  password: 
  socket: /Applications/MAMP/tmp/mysql/mysql.sock

The latest MySQL gem (=>0.3.2) needs an additional gem to connect -- it's been architected just like the MSSQL-Server gem was in previous versions of Rails.

You also probably want to use the mysql2 (note the "2") gem