db/migrate/20160822213716_add_null_false_to_bids_amount.rb
class AddNullFalseToBidsAmount < ActiveRecord::Migration
def up
execute <<-SQL
UPDATE bids
SET amount = 0
WHERE amount IS NULL;
SQL
change_column_null :bids, :amount, false
end
def down
change_column_null :bids, :amount, true
end
end