Normalize data in Rails Example

normalize.rb

class CreateAddresses < ActiveRecord::Migration
  def self.up
    create_table :addresses do |t|
      t.integer :customer_id
      t.string :address
      t.string :city
      t.string :state
      t.integer :zip_code
      t.timestamps
    end

    # move customer address fields to address table
    Customer.all.each do |c|
      Address.create({
        :customer_id => c.id,
        :address => c.address,
        :city => c.city,
        :state => c.state,
        :zip => c.zip
      })
    end

    # you'll have to write your own merge script here
    # use execute("your sql goes here...") if you can't do it with ActiveRecord methods

    # remove old customer address columns
    remove_columns(:customers, :address, :city, :state, :zip)

  end

  def self.down

    # here you will define the reverse of the self.up method

    # re-add the address columns to the user table

    # repopulate the customer table with data from the address table

    drop_table :addresses
  end
end