RoR : Migration

Little on ruby On rails Migration


Migrations: If you want to make any changes in the database, then migration come into picture.

How to create migration:
>>rails generate migration migration_name


It'll generate a file with file name as per conventions: 20120219053515_Migration_name.rb
Find this file under /db folder

Here you'll find rails has generated two methods for you:
def up
//write changes to be made
end
def down
// write changes to revert back above mentioned changes
end


Write any changes you want to make in database under this methods


How to run migration:
rake db:migrate:METHOD  VERSION=TIMESTAMP
eg
>> rake db:migrate:up VERSION=20120219053515


How to run all migrations files under /db folder
>>rake db:migrate


More on this here:
 http://guides.rubyonrails.org/migrations.html