Ruby On Rails

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Migration

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At the most basic level Migrations allow you to define incremental changes to your data model (and data itself!). This sort of approach melds seamlessly with Agile and XP methodologies favored by Rails developers the world over. A Migration is defined by subclassing ActiveRecord::Migration and overriding the two required method definitions, self.up and self.down:


class SampleMigration < ActiveRecord::Migration
def self.up
end

def self.down
end
end

Within the up and down definitions you can create tables and indexes, add data, manipulate models and more.