View source for Rails:Migrations

== Official Documentation ==
* https://guides.rubyonrails.org/active_record_migrations.html

== Schema Migrations ==
=== Generate a Migration ===
==== Add a Column ====

== Data Migrations ==
What if you need to do a data migration or data fix on existing data?

* https://thoughtbot.com/blog/data-migrations-in-rails
* https://github.com/dimroc/datafix