How to use activerecord with only ruby script

 # require 'mysql2'

require 'sqlite3'
require 'active_record'
require 'date'

# === GLOBAL variables ====
# date_time = DateTime.now
# curr_date_time = date_time.strftime "%d/%m/%Y  %H:%M:%S"
current_datetime = DateTime.now
puts current_datetime

# ===== establish connection ======
    ActiveRecord::Base.establish_connection( 
        :adapter => "sqlite3",
        :host => "localhost",
        :database => "../db/development.sqlite3"
       )
    # =====================
class Orders < ActiveRecord::Base
    self.table_name = 'orders'
        # has_many :table_relationship
end

# ========== query by activerecord =========

# === insert ===
order = Orders.new
order.buy_signal = ARGV[0]
order.buy_time = ARGV[1]
order.buy_order = ARGV[2]
order.buy_amount = ARGV[3]
order.buy_price = ARGV[4]
order.currency = ARGV[5]
order.save

# === select ===
orders = Orders.all 
puts orders.pluck(:currency, :buy_price)

abort "DEBUG =====> DONE"