# File lib/active_record/vendor/mysql.rb, line 219
  def change_user(user="", passwd="", db="")
    if @pre_411
      data = user+"\0"+scramble(passwd, @scramble_buff, @protocol_version==9)+"\0"+db
    else
      data = user+"\0"+scramble41(passwd, @scramble_buff)+db
    end
    pkt = command COM_CHANGE_USER, data
    handle_auth_fallback(pkt, passwd)
    @user = user
    @passwd = passwd
    @db = db
  end