discourse/db/migrate/20190117191606_create_group_requests.rb

class CreateGroupRequests < ActiveRecord::Migration[5.2]
  def change
    create_table :group_requests do |t|
      t.integer :group_id
      t.integer :user_id
      t.text :reason

      t.timestamps
    end

    add_index :group_requests, :group_id
    add_index :group_requests, :user_id
  end
end