Change database column type to decimal

问题

I am using Rails 3.2.3, and MySQL for my database
I have created a model affiliate_payment.rb, with a column :amount, initially with datatype float. I tried to change this to a decimal with the following migration:

class ChangeAffiliateIdAmountToDecimal < ActiveRecord::Migration
  def up
    change_column :affiliate_payments, :amount, :decimal
  end

  def down
    change_column :affiliate_payments, :amount, :float
  end
end

Ran rake db:migrate...
But when I check the column type to confirm, I find that the column type is now integer!

2.0.0-p353 :101 > AffiliatePayment.columns_hash["amount"].type
 => :integer 

Can someone explain what I am doing wrong?

回答1:

try this:

change_column :affiliate_payments, :amount, :decimal, :precision => 8, :scale => 2

This will become BigDecimal

回答2:

Use this with new ruby syntax:

change_column :affiliate_payments, :amount, :decimal, precision: 8, scale: 2

回答3:

Hey You have created the migration for change the column type so rake db:migrate need not be run.

You have to run the migration with there migration number like below

rake db:migrate:up VERSION = version number of migration.

来源：https://stackoverflow.com/questions/21699047/change-database-column-type-to-decimal