mac安装rails问题

gem install mysql2

brew install mysql 
gem install mysql2

http://stackoverflow.com/questions/12811489/installing-mysql2-gem-rails-on-mac

gem install pg

1. Make sure you have Xcode installed first.
2. Run: brew install postgresql
3. Add to your GemFile: gem 'pg'
4. Run: bundle install

http://stackoverflow.com/questions/18196054/gem-install-pg-on-mac-10-7-5