在终端窗口中使用 rails s 或 rail server 时，我收到以下消息。我在应用程序根目录中。有任何想法吗？
/Users/paul/.rvm/gems/ruby-2.0.0-p247/gems/mysql2-0.3.13/lib/mysql2.rb:8:in `require': dlopen(/Users/paul/.rvm/gems/ruby-2.0.0-p247/gems/mysql2-0.3.13/lib/mysql2/mysql2.bundle, 9): Library not loaded: libmysqlclient.18.dylib (LoadError)
Referenced from: /Users/paul/.rvm/gems/ruby-2.0.0-p247/gems/mysql2- 0.3.13/lib/mysql2/mysql2.bundle
Reason: image not found - /Users/paul/.rvm/gems/ruby-2.0.0-p247/gems/mysql2-0.3.13/lib/mysql2/mysql2.bundle
from /Users/paul/.rvm/gems/ruby-2.0.0-p247/gems/mysql2-0.3.13/lib/mysql2.rb:8:in `<top (required)>'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in `require'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in `block (2 levels) in require'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in `each'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in `block in require'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in `each'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in `require'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler.rb:132:in `require'
from /Users/paul/Documents/Ruby/simple_cms/config/application.rb:7:in `<top (required)>'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/railties-4.0.0/lib/rails/commands.rb:76:in `require'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/railties-4.0.0/lib/rails/commands.rb:76:in `block in <top (required)>'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/railties-4.0.0/lib/rails/commands.rb:73:in `tap'
from /Users/paul/.rvm/gems/ruby-2.0.0-p247@global/gems/railties-4.0.0/lib/rails/commands.rb:73:in `<top (required)>'
from bin/rails:4:in `require'
from bin/rails:4:in `<main>'