A cheat sheet for Rail's Active Record.

ActiveRecord.md

Assume we have model Car

# Get all cars with color red
Car.where( color: "red" )

Retrieve all users that have field 'company' not nil

  users = Spree::User.where("spree_users.company IS NOT NULL")

Retrieve user with id 1 and display only 'id' and 'email'

  Spree::User.where(id: 1).select('email')

http://api.rubyonrails.org/classes/ActiveRecord/Calculations.html#method-i-pluck

Person.pluck(:id) # SELECT people.id FROM people
Person.uniq.pluck(:role) # SELECT DISTINCT role FROM people
Person.where(:confirmed => true).limit(5).pluck(:id)