ActiveRecord::ConnectionNotEstablished error when using has_and_belongs_to_many

I am running into ActiveRecord::ConnectionNotEstablished error.

I have the following code

ActiveRecord::Base.establish_connection(:adapter => 'sqlite3', :database => 'users_vendors.db')

Class User < ActiveRecord::Base
   has_and_belongs_to_many :vendors
end

class Vendor < ActiveRecord::Base
   has_and_开发者_JAVA百科belongs_to_many :users
end

I am new to active records in ruby so any help would be appreciated

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Is there any reason why you are connecting to the database in this fashion? The best way to do that is through a database.yml. http://wiki.rubyonrails.org/database-support/mysql#databaseyml_example

[Edit] For sqlite: http://wiki.rubyonrails.org/database-support/sqlite#databaseyml_example