Add Rollback A Specific Migration Out Of Order as a Rails migration

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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 - [Render The Response Body In Controller Specs](rails/render-the-response-body-in-controller-specs.md)
 - [Rescue From](rails/rescue-from.md)
 - [Retrieve An Object If It Exists](rails/retrieve-an-object-if-it-exists.md)
+- [Rollback A Specific Migration Out Of Order](rails/rollback-a-specific-migration-out-of-order.md)
 - [Rounding Numbers With Precision](rails/rounding-numbers-with-precision.md)
 - [Schedule Sidekiq Jobs Out Into The Future](rails/schedule-sidekiq-jobs-out-into-the-future.md)
 - [Secure Passwords With Rails And Bcrypt](rails/secure-passwords-with-rails-and-bcrypt.md)

rails/rollback-a-specific-migration-out-of-order.md

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+# Rollback A Specific Migration Out Of Order
+
+If you want to rollback the latest migration that is `up`, you can use:
+
+```bash
+$ rails db:rollback
+```
+
+It deals explicitly with the latest `up` migration and nothing else. Even if
+you name a specific `VERSION`, it will still just rollback the one latest.
+
+Instead, if you want to target a specific past migration for rollback, you'll
+want the `db:migrate:down` command. You'll need to specify the version, which
+is the timestamp number in the filename of the migration.
+
+Here is what this looks like for a recent migration I had to rollback.
+
+```bash
+$ rails db:migrate:down VERSION=20210302171858
+```
+
+[source](https://stackoverflow.com/a/3647820/535590)