Railsドキュメント(v6.0.2.1)

class AddSsl < ActiveRecord::Migration
  def up
    add_column :accounts, :ssl_enabled, :boolean, default: true
  end

  def down
    remove_column :accounts, :ssl_enabled
  end
end

class TenderloveMigration < ActiveRecord::Migration
  def change
    create_table(:horses) do |t|
      t.column :content, :text
      t.column :remind_at, :datetime
    end
  end
end

def up
end

def up
  create_table :pages do |t|
    t.string :name
    t.string :category
  end
end

def down
end

def down
  drop_table :pages
end

change(カラム名, 型 [, オプション])

t.change(:description, :text)

t.change(:name, :string, limit: 80)

create_table(テーブル名 [, オプション])

create_table テーブル名  [, オプション] do |t|
  t.型 カラム名 [, カラムオプション]
end

crate_table :products do |t|
  t.string :name
end

create_tabe :products |t|
  t.string :name, null: false
end

create_table :suppliers, options: 'ENGINE=InnoDB DEFAULT CHARSET=utf8'

create_table(:objects, primary_key: 'guid') do |t|
  t.column :name, :string, limit: 80
end

create_table(:categories_suppliers, id: false) do |t|
  t.column :category_id, :integer
  t.column :supplier_id, :integer
end

rename_table(現在のテーブル名, 新しいテーブル名)

rename_table :now_table, :new_table

drop_table(:テーブル名 [, オプション])

drop_table :products

drop_table :care_reasons, force: :cascade

drop_table :article_attributes, if_exists: true

change_table(テーブル名 [, オプション]) do |t|
  t.メソッド名(データ型) カラム名
end

change_table :pages do |t|
  t.text :memo
  t.index :title
end

change_table(:suppliers) do |t|
  t.column :name, :string, limit: 60
end

change_table(:suppliers) do |t|
  t.integer :width, :height, null: false, default: 0
end

change_table(:suppliers) do |t|
  t.timestamps
end

change_table(:suppliers) do |t|
  t.references :company
end

change_table(:suppliers) do |t|
  t.remove :company_id
  t.remove :width, :height
end

change_table(:suppliers) do |t|
  t.remove_index :company_id
end

create_join_table(テーブル名1, テーブル名2 [, オプション])

create_join_table(:assemblies, :parts, options: 'ENGINE=InnoDB DEFAULT CHARSET=utf8')
# CREATE TABLE assemblies_parts (
#   assembly_id int NOT NULL,
#   part_id int NOT NULL,
# ) ENGINE=InnoDB DEFAULT CHARSET=utf8

table_exists?(テーブル名)

table_exists?(:developers)

drop_join_table(テーブル1, テーブル2 [, オプション])

drop_join_table(:assemblies, :parts)

drop_join_table(:assemblies, :parts, options: 'ENGINE=InnoDB DEFAULT CHARSET=utf8')

add_column(テーブル名 カラム名, タイプ [, オプション])

add_column :users, :group_id, :integer

add_column :users, :picture, :binary, limit: 2.megabytes
# ALTER TABLE "users" ADD "picture" blob(2097152)

add_column :articles, :status, :string, limit: 20, default: 'draft', null: false
# ALTER TABLE "articles" ADD "status" varchar(20) DEFAULT 'draft' NOT NULL

add_column :answers, :bill_gates_money, :decimal, precision: 15, scale: 2
# ALTER TABLE "answers" ADD "bill_gates_money" decimal(15,2)

add_column :users, :skills, :text, array: true
# ALTER TABLE "users" ADD "skills" text[]

add_column :shapes, :triangle, 'polygon'
# ALTER TABLE "shapes" ADD "triangle" polygon

rename_column(テーブル名, 変更するカラム名, 新しいカラム名)

rename_column :suppliers, :description, :name

change_column(テーブル名,  カラム名, データ型 [, オプション])

change_column(:users, :name, :text)

change_column(:users, :name, :string, limit: 80)

change_column(:users, :name, :string, null: dalse)

remove_column(テーブル名, カラム名 [, 型, オプション])

remove_column :users, :description

remove_column :users, :description, :string, limit: 20

remove_columns(テーブル名, カラム名 [, ...])

remove_columns(:suppliers, :qualification, :experience)

change_column_default(テーブル名, カラム名, 初期値)

change_column_default(:suppliers, :qualification, 'new')

change_column_default(:users, :email, nil)

change_column_comment(テーブル名, カラム名, comment_or_changes)

change_column_comment :posts, :state, from: "old_comment", to: "new_comment"

change_column_comment :posts, :state, nil

change_column_null(table_name, column_name, null, default = nil)

change_column_null(:users, :nickname, false)

change_column_null(:users, :nickname, true)

change_table_comment(テーブル名, コメント)

change_table_comment :posts, from: "old_comment", to: "new_comment"

change_table_comment :posts, nil

column_exists?(テーブル名, カラム名 [, 型, オプション])

column_exists? :pages, :title

column_exists? :suppliers, :name, :string

column_exists?(:suppliers, :name, :string, null: false)

add_index(テーブル名, インデックスを付与するカラム名 [, オプション])

add_index :users, :name

add_index :users, [:name, :employee_id], unique: true

add_index :users, [:name, :employee_id], unique: true, name: 'by_branch_name'

add_index :users, :name, name: 'by_name', length: 10

add_index :accounts, [:name, :surname], name: 'by_name_surname', length: {name: 10, surname: 15}

add_index :accounts, [:branch_id, :party_id, :surname], order: {branch_id: :desc, party_id: :asc}

add_index :accounts, [:branch_id, :party_id], unique: true, where: "active"

add_index :developers, :name, using: 'btree'

add_index :developers, :name, using: 'gist', opclass: :gist_trgm_ops

add_index :developers, :name, type: :fulltext

add_index :developers, :name, algorithm: :concurrently

rename_index(テーブル名, 変更前の名前, 変更後の名前)

rename_index :people, 'index_people_on_last_name', 'index_users_on_last_name'

remove_index(テーブル名 [, オプション])

remove_index :users, :name

remove_index :accounts, column: :branch_id

remove_index :accounts, column: [:branch_id, :party_id]

remove_index :accounts, name: :by_branch_party

remove_index :accounts, name: :by_branch_party, algorithm: :concurrently

index_exists?(テーブル名, カラム名 [, オプション])

index_exists? :pages, :title

index_exists?(:suppliers, [:company_id, :company_type]

index_exists?(:suppliers, :company_id, unique: true)

index_exists?(:suppliers, :company_id, name: "idx_company_id")

index_name_exists?(テーブル名, インデックス名)

index_name_exists?(:pages, :title)

timestamps

create_table :users do |t|
  t.timestamps
end

add_timestamps(テーブル名)

add_timestamps :users

add_timestamps :suppliers, null: true

remove_timestamps(テーブル名)

remove_timestamps(:users)

references(カラム名 [, オプション])

t.references(:user)

add_reference(テーブル名, リファレンス名 [, オプション])

add_reference(:products, :user)

add_reference(:products, :user, type: :string)

add_reference(:products, :supplier, index: { unique: true })

add_reference(:products, :supplier, foreign_key: true)

add_reference(:products, :user, null: false)

remove_reference(テーブル名, リファレンス名 [, オプション])

remove_reference(:products, :user, index: true)

remove_reference(:products, :supplier, polymorphic: true)

remove_reference(:products, :user, foreign_key: true)

execute(SQL文)

execute "SELECT * FROM pages ORDER BY updated_at DESC LIMIT 10"