class AddInitialBalanceToAccount < ActiveRecord::Migration
  def self.up
    add_column :accounts, :initialBalance, :decimal, :scale => 2, :precision => 15, :default => 0.00
  end
 
  def self.down
    remove_column :accounts, :initialBalance
  end
end
 

>> a = Account.new(:name => "Test Account", :initialBalance => 9.999)
=> #<Account id: nil, name: "Test Account", created_at: nil, updated_at: nil, initialBalance: #<BigDecimal:b6f889a8,'0.9999E1',8(8)>>
>> a.initialBalance.to_s
=> "9.999"
>> a.save
=> true
>> a.initialBalance.to_s
=> "9.999"
>> a.initialBalance = 12345678901234567890
=> 12345678901234567890
>> a.initialBalance.to_s
=> "12345678901234567890.0"