Rails Activerecord Queries

Queries using ActiveRecord
 1# Simple queries return collections of instances
 2        Article.all
 3        Article.find(3) # id=3
 4        Article.w­her­e(a­uthor: 'admin')
 5        Article.where("likes_count = ?", value_for_count)
 6        Article.f­ind­_by­(title: 'Rails 4', author: 'admin')
 7        Article.find_or_create_by(title: 'Beatles')
 8
 9# Working with collections
10        Article.where(author: 'pito').last # choosing
11        Article.where(author: 'pito').order(created_at: :desc) # sorting
12
13# Working with associated Models
14article = Article.comments.where(author: 'georg')
15
16# What is the sql for a certain query?
17Department.sample.people.samle.to_sql
18