The Life‑Changing Magic of Ruby and Rails

How to Drop a Table in Rails

So you created a migration to add a table that you thought you were going to need. You also ran that migration so that table is in your database. Now, you don’t need it anymore and want to drop it from the database. How do you remove that table?

Step 1: Generate a migration

Run the following command to create a new migration named DropArticles where articles is the table name.

➜  blog (main) ✗ bin/rails generate migration DropArticles

Step 2: Use the drop_table method

The drop_table method takes the table name as an argument and instructs rails to drop that table from the database when running the migration.

class DropArticles < ActiveRecord::Migration[6.1]
  def change
    drop_table :articles
  end
end

Step 3: Run the migration

To execute the above code to drop the table, run the database migration.

➜  blog (main) ✗ bin/rails db:migrate

Congratulations, you just dropped the table. If you change your mind again and want to recreate the table, reverse the migration using the db:rollback command.

Warning: Remember that fully reversing this migration is not possible. So if you rollback this migration, Rails will create an empty table. When you drop a table, you also get rid of all the data it contains. You won’t get back the data the table had before deletion.

Additional Parameters

You can provide the following options to the drop_table call.

  • :force: Use it to drop dependent objects by setting the value to :cascade. It defaults to false.
drop_table :articles, force: :cascade
  • if_exists: Set it to true, to only drop the table if it exists. It defaults to false, too.
drop_table :articles, if_exists: true

Drop table without migration

There is another way to drop the table without using a migration. Enter the rails console, and tell the ActiveRecord::Migration class to drop that table.

➜  bin/rails c
Running via Spring preloader in process 97140
Loading development environment (Rails 6.1.4.1)

3.0.2 :001 > ActiveRecord::Migration.drop_table :articles
-- drop_table(:articles)
   (20.0ms)  DROP TABLE "articles"
   -> 0.0980s
 => #<PG::Result:0x00007fa5d7ee21e8 status=PGRES_COMMAND_OK ntuples=0 nfields=0 cmd_tuples=0>
3.0.2 :002 >

I hope that helps! Let me know if you have any questions.


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