Rails DB Migration - How To Drop a Table?

Question

I added a table that I thought I was going to need, but now no longer plan on using it. How should I remove that table?

I've already run migrations, so the table is in my database. I figure rails generate migration should be able to handle this, but I haven't figured out how yet.

I've tried:

rails generate migration drop_tablename 

but that just generated an empty migration.

What is the "official" way to drop a table in Rails?

Answer 1

You won't always be able to simply generate the migration to already have the code you want. You can create an empty migration and then populate it with the code you need.

You can find information about how to accomplish different tasks in a migration here:

http://api.rubyonrails.org/classes/ActiveRecord/Migration.html

More specifically, you can see how to drop a table using the following approach:

drop_table :table_name 

Answer 2

First generate an empty migration with any name you'd like. It's important to do it this way since it creates the appropriate date.

rails generate migration DropProductsTable 

This will generate a .rb file in /db/migrate/ like 20111015185025_drop_products_table.rb

Now edit that file to look like this:

class DropProductsTable < ActiveRecord::Migration   def up     drop_table :products   end    def down     raise ActiveRecord::IrreversibleMigration   end end 

The only thing I added was drop_table :products and raise ActiveRecord::IrreversibleMigration.

Then run rake db:migrate and it'll drop the table for you.