There are multiple ways of running migrations from the console. This might be the easiest one to remember:
```ruby
irb ActiveRecord::Schema
add_index :followers, [:leader_id, :follower_id], :unique => true
```
You can also paste the migration code into the console window:
```ruby
class ModifyRating < ActiveRecord::Migration
def self.up
change_column :products, :rating, :decimal, :precision => 5, :scale => 3
end
def self.down
end
end
```
Run the migration by typing **ModifyRating.up**.