我在使用rails连接到mysql数据库时遇到问题。我是rails的新手，但我 在这里尝试了指南：
rails + MySQL on OSX: Library not loaded: libmysqlclient.18.dylib
这仍然不起作用。我相信我安装了两个mysql安装，这让人感到困惑。
我安装了MAMP和它自己的mysql，我也安装了rails mysql2 gem。当我按照上面提供的链接中的步骤进行操作时，我认为这是使用MAMP mysql安装而不是使用rails gems的mysql2安装，因此它无法识别它。
有什么方法可以将两个mysql合并为一个？或者更容易修改rails以便它可以看到mysql2 gem？
~/Sites/RoR3-Essentials/simple_cms ->rails s
=＆GT;启动WEBrick
=＆GT; Rails 3.2.13应用程序从http://localhost:3000
=＆GT;使用-d调用分离
=＆GT; Ctrl-C关闭服务器
退出
/Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/mysql2-0.3.11/lib/mysql2/client.rb:44:in `connect'：未知数据库'simple_cms_development'（Mysql2 :: Error）
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/mysql2-0.3.11/lib/mysql2/client.rb:44:in `initialize'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/mysql2_adapter.rb:16:in `new'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/mysql2_adapter.rb:16:in `mysql2_connection'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:315:in `new_connection'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:325:in `checkout_new_connection'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:247:in `block (2 levels) in checkout'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `loop'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `block in checkout'
from /Users/markmilly/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:239:in `checkout'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:102:in `block in connection'
from /Users/markmilly/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:101:in `connection'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:410:in `retrieve_connection'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_specification.rb:171:in `retrieve_connection'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_specification.rb:145:in `connection'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/activerecord-3.2.13/lib/active_record/railtie.rb:88:in `block in <class:Railtie>'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/initializable.rb:30:in `instance_exec'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/initializable.rb:30:in `run'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/initializable.rb:55:in `block in run_initializers'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/initializable.rb:54:in `each'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/initializable.rb:54:in `run_initializers'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/application.rb:136:in `initialize!'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/railtie/configurable.rb:30:in `method_missing'
from /Users/markmilly/Sites/RoR3-Essentials/simple_cms/config/environment.rb:5:in `<top (required)>'
from /Users/markmilly/Sites/RoR3-Essentials/simple_cms/config.ru:3:in `require'
from /Users/markmilly/Sites/RoR3-Essentials/simple_cms/config.ru:3:in `block in <main>'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.4.5/lib/rack/builder.rb:51:in `instance_eval'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.4.5/lib/rack/builder.rb:51:in `initialize'
from /Users/markmilly/Sites/RoR3-Essentials/simple_cms/config.ru:in `new'
from /Users/markmilly/Sites/RoR3-Essentials/simple_cms/config.ru:in `<main>'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.4.5/lib/rack/builder.rb:40:in `eval'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.4.5/lib/rack/builder.rb:40:in `parse_file'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.4.5/lib/rack/server.rb:200:in `app'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands/server.rb:46:in `app'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.4.5/lib/rack/server.rb:304:in `wrapped_app'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.4.5/lib/rack/server.rb:254:in `start'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands/server.rb:70:in `start'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands.rb:55:in `block in <top (required)>'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands.rb:50:in `tap'
from /Users/markmilly/.rvm/gems/ruby-2.0.0-p0/gems/railties-3.2.13/lib/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
答案 0 :(得分：0)
@markmilly回答你的上一条评论：
'rake db：create'创建你在config / database.yml文件中指定的数据库。
它将为您当前的RAILS_ENV创建数据库。如果未指定环境，则默认为开发和测试db。
我看到这个答案有点晚了，但它可能对其他人有帮助。