parse error when running oracle stored procedure through rails

I am running to run an oracle stored procedure in rails, but I am getting the following error:

ActionView::Template::Error (undefined method `parse' for
#<Mysql2::Client:0x00000008ef4310>):

in the following line:

   cursor = connection.parse(sql)

This is my database.yml file

development:
  adapter:  mysql2
  database: db1
  username: user1
  password: *****
  host:     *****
  port:     3306

db1_development:
  adapter: mysql2
  username: user2
  password: ****
  database: ****
  host: *****
  port: 3306

db2_development:
  adapter: mysql2
  database: user3
  username: ******
  password: ******
  host: *****
  port: 3309

db3_development:
  adapter: oracle_enhanced
  database: user3
  username: *****
  password: *****

these are my 2 model classes:

module Sts

  class StsLtd < Sts::Base
    def number
        errormsg = nil
        errorcode = nil
        sperrormsg = nil
        vpan = nil

        sql =
      "BEGIN #{Pkgltd::PKG_LTD}.GET_PAN('
        8042049440330819','32', 'TEST', '0',vpan, errormsg, errorcode, sperrormsg);
       END;"

       connection = self.connection.raw_connection
       cursor = connection.parse(sql)

         cursor.bind_param(:errormsg, nil, String, 1000)
         cursor.bind_param(:errorcode, nil, String, 1000)
         cursor.bind_param(:sperrormsg, nil, String, 1000
             cursor.bind_param(:vpan, nil, String, 1000)

       cursor.exec

       vpan, errormsg, errorcode, sperrormsg, vpan = cursor[:vpan], cursor[:errormsg], cursor[:errorcode], cursor[:sperrormsg]
       cursor.close
       vpan
    end
  end
end

sts.rb:

module Sts

  PKG_LTD ="PKG_LTD"

  class Base < ActiveRecord::Base
    self.abstract_class = true
    establish_connection = "db3_#{Rails.env}"

  end
end

I am not sure why it is throwing mysql parse error, when the specific set of code is only trying to connect to the oracle database and running the oracle stored procedure.