briu

a = true and false

puts a

a = true && false

puts a

briu

module A
  def test
    puts "module A"
  end
end

module B
  def test
    puts "module B"
  end

briu

module A
  def self.test
    "FOO"
  end
end

module Yo
  module A
    def self.test
      "BAR"

briu

class CallCenter < ActiveRecord::Base

  def self.prepare_to_work
    all.each do |call_center|
      if call_center.name == 'test1'
        call_center.check_callmanagers
        call_center.update_attributes(handled: 0)
      elsif call_center.name == 'test2'
        call_center.send_letters_to_customers
        call_center.remove_managers

briu

class Finance < ActiveRecord::Base
  validate :check_amount

  def check_amount
    errors.add(:check_amount, 'quantity limit over!') if amount > 100
  end
end

first = Finance.first
second = Finance.last

briu

class Client
  attr_reader :item
  
  def initialize(item)
    @item = item  
  end
  
  def calculate_something
    80 * 20
  end

briu

module AddMePlease
  def some_useful_method
    2 + 2
  end
  
  def second_useful_method
    2 * 3
  end
end

briu

CREATE TABLE customers (
    source_id integer,
    name varchar(255)
);

INSERT INTO customers (source_id, name) values (null, 't1'), (1, 't2'), (2, 't3'), (3, 't5'), (null, 't5');

SELECT COUNT(*) FROM customers WHERE source_id <> 3;

briu

CREATE TABLE orders (
    id integer,
    name varchar(255),
    address varchar(255)
);

CREATE TABLE order_items (
    id integer,
    price integer,
    order_id integer,

briu

class A
  private
  
  def some_method
    puts 'HOLA!'
  end
end

class B < A
  def test_some_method_exec