Ruby on rails I'；我试着将designe与pg'一起使用；0.15.1'；。当我尝试运行迁移时，出现以下错误

错误

迁移文件

 DeviseCreateUsers: migrating ================================
-- create_table(:users)
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

PG::Error: ERROR:  relation "users" already exists
: CREATE TABLE "users" ("id" serial primary key, "email" character varying(255) DEFAULT '' NOT NULL, "encrypted_password" character varying(255) DEFAULT '' NOT NULL, "reset_password_token" character varying(255)

class AddDevisionToUsers

错误代码非常简单……表“users”已经存在。再次尝试迁移我已尝试删除该表，但没有任何帮助。这是我的迁移。对格式错误表示歉意。请输入您的数据库控制台（类型

rails dbconsole

）并向我显示表列表（在数据库控制台类型

\d

）谢谢您的编辑和回复JTG！我设法把它分类了，但不太清楚如何分类。仍然向前和向上。

class AddDeviseToUsers < ActiveRecord::Migration
  def self.up
    change_table(:users) do |t|
      ## Database authenticatable
      t.string :email,              null: false, default: ""
      t.string :encrypted_password, null: false, default: ""

      ## Recoverable
      t.string   :reset_password_token
      t.datetime :reset_password_sent_at

      ## Rememberable
      t.datetime :remember_created_at

      ## Trackable
      t.integer  :sign_in_count, default: 0, null: false
      t.datetime :current_sign_in_at
      t.datetime :last_sign_in_at
      t.string   :current_sign_in_ip
      t.string   :last_sign_in_ip

      ## Confirmable
      # t.string   :confirmation_token
      # t.datetime :confirmed_at
      # t.datetime :confirmation_sent_at
      # t.string   :unconfirmed_email # Only if using reconfirmable

      ## Lockable
      # t.integer  :failed_attempts, default: 0, null: false # Only if lock strategy is :failed_attempts
      # t.string   :unlock_token # Only if unlock strategy is :email or :both
      # t.datetime :locked_at


      # Uncomment below if timestamps were not included in your original model.
      # t.timestamps
    end

    add_index :users, :email,                unique: true
    add_index :users, :reset_password_token, unique: true
    # add_index :users, :confirmation_token,   unique: true
    # add_index :users, :unlock_token,         unique: true
  end

  def self.down
    # By default, we don't want to make any assumption about how to roll back a migration when your
    # model already existed. Please edit below which fields you would like to remove in this migration.
    raise ActiveRecord::IrreversibleMigration
  end
end