我刚学会ruby on rails。我想用mysql代替sqlite3。这是我的配置：
配置/database.yml

default: &default
  adapter: mysql
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  timeout: 5000
development:
  <<: *default
  database: library_development
  username: root
  password: ""
  host: localhost
# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: library_test
  username: root
  password: ""
  host: localhost
production:
  <<: *default
  database: library_production
  username: root
  password: ""
  host: localhost

gemfile公司

source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }
ruby '2.5.1'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 5.2.1'
# Use mysql as the database for Active Record
gem 'mysql', '~> 2.9.1'
gem 'mysql2', '~> 0.3.13'
# Use Puma as the app server
gem 'puma', '~> 3.11'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# See https://github.com/rails/execjs#readme for more supported runtimes
gem 'duktape'
# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.2'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.5'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'
# Use ActiveStorage variant
# gem 'mini_magick', '~> 4.8'
# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development
# Reduces boot times through caching; required in config/boot.rb
gem 'bootsnap', '>= 1.1.0', require: false
group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
end
group :development do
  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
  gem 'web-console', '>= 3.3.0'
end
group :test do
  # Adds support for Capybara system testing and selenium driver
  gem 'capybara', '>= 2.15'
  gem 'selenium-webdriver'
  # Easy installation and use of chromedriver to run system tests with Chrome
  gem 'chromedriver-helper'
end
# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

当我跑的时候 bundle install 它返回错误：
gem文件仍将安装在c:/ruby25-x64/lib/ruby/gems/2.5.0/gems/mysql-2.9.1中以供检查。结果记录到c:/ruby25-x64/lib/ruby/gems/2.5.0/extensions/x64-mingw32/2.5.0/mysql-2.9.1/gem\u make.out
安装mysql（2.9.1）时出错，bundler无法继续。确保 gem install mysql -v '2.9.1' --source 'https://rubygems.org/' 绑定前成功。
在文件中：mysql
请帮忙。谢谢您。