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Make it clear what a migration is. #1263

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Make it clear what a migration is. #1263

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2 changes: 1 addition & 1 deletion source/projects/blogger.markdown
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Expand Up @@ -112,7 +112,7 @@ Rails uses migration files to perform modifications to the database. Almost any

#### Migration?

What is a migration? Let's open `db/migrate/(some_time_stamp)_create_articles.rb` and take a look. First you'll notice that the filename begins with a mish-mash of numbers which is a timestamp of when the migration was created. Migrations need to be ordered, so the timestamp serves to keep them in chronological order. Inside the file, you'll see just the method `change`.
What is a migration? A migration is a way to alter your database's schema. Let's open `db/migrate/(some_time_stamp)_create_articles.rb` and take a look. First you'll notice that the filename begins with a mish-mash of numbers which is a timestamp of when the migration was created. Migrations need to be ordered, so the timestamp serves to keep them in chronological order. Inside the file, you'll see just the method `change`.

Migrations used to have two methods, `up` and `down`. The `up` was used to make your change, and the `down` was there as a safety valve to undo the change. But this usually meant a bunch of extra typing, so with Rails 3.1 those two were replaced with `change`.

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