How to drop columns using Rails migration

remove_column :table_name, :column_name

For instance:

remove_column :users, :hobby

would remove the hobby Column from the users table.

For older versions of Rails

ruby script/generate migration RemoveFieldNameFromTableName field_name:datatype

For Rails 3 and up

rails generate migration RemoveFieldNameFromTableName field_name:datatype

Rails 4 has been updated, so the change method can be used in the migration to drop a column and the migration will successfully rollback. Please read the following warning for Rails 3 applications:

Rails 3 Warning

Please note that when you use this command:

rails generate migration RemoveFieldNameFromTableName field_name:datatype

The generated migration will look something like this:

  def up
    remove_column :table_name, :field_name
  end

  def down
    add_column :table_name, :field_name, :datatype
  end

Make sure to not use the change method when removing columns from a database table (example of what you don't want in the migration file in Rails 3 apps):

  def change
    remove_column :table_name, :field_name
  end

The change method in Rails 3 is not smart when it comes to remove_column, so you will not be able to rollback this migration.

In a rails4 app it is possible to use the change method also for removing columns. The third param is the data_type and in the optional forth you can give options. It is a bit hidden in the section 'Available transformations' on the documentation .

class RemoveFieldFromTableName < ActiveRecord::Migration
  def change
    remove_column :table_name, :field_name, :data_type, {}
  end
end

There are two good ways to do this:

remove_column

You can simply use remove_column, like so:

remove_column :users, :first_name

This is fine if you only need to make a single change to your schema.

change_table block

You can also do this using a change_table block, like so:

change_table :users do |t|
  t.remove :first_name
end

I prefer this as I find it more legible, and you can make several changes at once.

Here's the full list of supported change_table methods:

http://apidock.com/rails/ActiveRecord/ConnectionAdapters/SchemaStatements/change_table