author = Author.create(name: 'Yukihiro Matsumoto')
#    (0.1ms)  begin transaction
#   Author Create (0.6ms)  INSERT INTO "authors" ("id", "name", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["id", "9bf631fc-6bed-4cb0-b062-102476609451"], ["name", "Yukihiro Matsumoto"], ["created_at", "2019-06-06 02:18:45.011828"], ["updated_at", "2019-06-06 02:18:45.011828"]]
#    (4.5ms)  commit transaction
# => #<Author id: "9bf631fc-6bed-4cb0-b062-102476609451", name: "Yukihiro Matsumoto", created_at: "2019-06-06 02:18:45", updated_at: "2019-06-06 02:18:45">

Book.create(title: 'The Ruby Programming Language', author: author)
#    (0.1ms)  begin transaction
#   Book Create (0.4ms)  INSERT INTO "books" ("id", "title", "author_id", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?)  [["id", "1ae09f6e-59e5-4cb2-b963-a1ea70a81bc1"], ["title", "The Ruby Programming Language"], ["author_id", "9bf631fc-6bed-4cb0-b062-102476609451"], ["created_at", "2019-06-06 02:18:45.032894"], ["updated_at", "2019-06-06 02:18:45.032894"]]
#    (4.6ms)  commit transaction
# => #<Book id: "1ae09f6e-59e5-4cb2-b963-a1ea70a81bc1", title: "The Ruby Programming Language", author_id: "9bf631fc-6bed-4cb0-b062-102476609451", created_at: "2019-06-06 02:18:45", updated_at: "2019-06-06 02:18:45">

Book.create(title: 'Ruby Best Practices', author: author)
#    (0.1ms)  begin transaction
#   Book Create (0.4ms)  INSERT INTO "books" ("id", "title", "author_id", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?)  [["id", "2bacf441-66dc-43d4-9548-4a4839be88e2"], ["title", "Ruby Best Practices"], ["author_id", "9bf631fc-6bed-4cb0-b062-102476609451"], ["created_at", "2019-06-06 02:18:54.957490"], ["updated_at", "2019-06-06 02:18:54.957490"]]
#    (6.8ms)  commit transaction
# => #<Book id: "2bacf441-66dc-43d4-9548-4a4839be88e2", title: "Ruby Best Practices", author_id: "9bf631fc-6bed-4cb0-b062-102476609451", created_at: "2019-06-06 02:18:54", updated_at: "2019-06-06 02:18:54">