ruby无法连接MySQL

我是RubyonRails新手，我正在尝试让它与MySQL一起工作。我使用brew安装mysql安装了mysql，然后安装了gem mysql2，但没有任何效果。我已经把这里所有的问题都讨论过了，似乎什么都不管用。这是我的数据库.yml

    # MySQL.  Versions 5.0+ are recommended.
      #
      # Install the MYSQL driver
      #   gem install mysql2
      #
      # Ensure the MySQL gem is defined in your Gemfile
      #   gem 'mysql2'
      #
      # And be sure to use new-style password hashing:
      #   http://dev.mysql.com/doc/refman/5.0/en/old-client.html
      #
      default: &default
        adapter: mysql2
        encoding: utf8
        pool: 5
        username: root
        password:
        host: localhost

      development:
        <<: *default
        database: optimus_development

      # 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: optimus_test

      # As with config/secrets.yml, you never want to store sensitive information,
      # like your database password, in your source code. If your source code is
      # ever seen by anyone, they now have access to your database.
      #
      # Instead, provide the password as a unix environment variable when you boot
      # the app. Read http://guides.rubyonrails.org/configuring.html#configuring-a-database
      # for a full rundown on how to provide these environment variables in a
      # production deployment.
      #
      # On Heroku and other platform providers, you may have a full connection URL
      # available as an environment variable. For example:
      #
      #   DATABASE_URL="mysql2://myuser:mypass@localhost/somedatabase"
      #
      # You can use this database configuration with:
      #
      #   production:
      #     url: <%= ENV['DATABASE_URL'] %>
      #
      production:
        <<: *default
        database: optimus_production
        username: optimus
        password: <%= ENV['OPTIMUS_DATABASE_PASSWORD'] %>

我曾尝试将localhost更改为127.0.0.1，但没有成功。如有任何协助，将不胜感激

我在阅读了下面可能存在的重复链接后启动了服务器，现在收到以下消息：

          Unknown database 'optimus_development'Run `$ bin/rake db:create db:migrate` to create your database

---

确保您的MySQL服务器已启动：

Apple Menu > System Preferences > MySQL > Start MySQL Server

---

我想出来了。我必须使用“mysql.server start”从终端运行mysql服务器。然后我不得不运行“bin/rake db:create db:migrate”，然后它就开始工作了

那么你会遇到什么错误？请始终发布你遇到的错误。本地MySQL服务的一个常见问题是，它们运行在Unix套接字上，其文件不在默认的预期位置，要求您在database.ymlAnd中添加一个

socket:/path/to/mysql.sock

，您说您确实安装了

brew mysql

，但是您真的启动了mysql服务器吗？您能在没有Rails的情况下从命令行连接到它吗？Michael Berkowski，我何时添加“socket:/path/to/mysql.sock”？Mysql甚至没有显示在系统首选项窗口中。这是因为我已经安装了mamp，并且它干扰了brew安装的mysql吗？只有使用了具有首选项窗格扩展的mysql安装程序时，这才相关。

Apple Menu > System Preferences > MySQL > Start MySQL Server