错误1:ActiveRecord::StatementInvalid
/home/diudiugirl/.rvm/gems/ruby-2.1.3/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:243:in `query’: Mysql2::Error: Table ‘ashelf_development.accounts’ doesn’t exist: SHOW FULL FIELDS FROM `accounts` (ActiveRecord::StatementInvalid)
…..
解决方法：
database.yml中配置了三种环境，使用不同的数据库：development、test和production，而默认的是development环境。而在上述错误中未指定production环境，让我们使用rails s -e prodution来指定，又出现了如下的错误2。
错误2：ActiveRecord::AdapterNotSpecified
/home/diudiugirl/.rvm/gems/ruby-2.1.3/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/connection_specification.rb:47:in `resolve_hash_connection’: database configuration does not specify adapter (ActiveRecord::AdapterNotSpecified)
解决方法：使用 RAILS_ENV=production rails s 命令来指定。
错误3：Errno::EADDRINUSE
/home/diudiugirl/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/socket.rb:206:in `bind’: Address already in use – bind(2) for 0.0.0.0:3000 (Errno::EADDRINUSE)
解决方法：已经有一个rails s在运行了。
错误4：ExecJS::RuntimeUnavailable
/home/diudiugirl/.rvm/gems/ruby-2.1.3/gems/execjs-2.2.2/lib/execjs/runtimes.rb:51:in `autodetect’: Could not find a JavaScript runtime. See https://g`ithub.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)
解决方法：
按照错误提示ExecJS缺失runtime，查看链接https://g`ithub.com/sstephenson/execjs 可看到，ExecJS所支持的runtime：
- therubyracer – Google V8 embedded within Ruby
- therubyrhino – Mozilla Rhino embedded within JRuby
- Node.js
- Apple JavaScriptCore – Included with Mac OS X
- Microsoft Windows Script Host (JScript)
而通过“ExecJS lets you run JavaScript code from Ruby. It automatically picks the best runtime available to evaluate your JavaScript program, then returns the result to you as a Ruby object.”可以看到，ExecJS会自动选择一个最好的现有runtime，所以能装的gems都装一下吧。
有两种方法：一是，使用gem install therubyracer和sudo apt-get install nodejs。二是在Gemfile中加入gem ‘execjs’，并将“#gem ‘therubyracer’, platforms: :ruby”前的注释去掉。