Mac 下 Rails 使用 MySQL 驱动的问题：Library not l?报错

给 Rails 配置了 MySQL：

development:
  adapter: mysql2
  encoding: utf8
  database: mydb
  username: root
  password: 
  host: 127.0.0.1
  port: 3306

执行 bin/rake db:migrate 时报错：

LoadError: dlopen(/Library/Ruby/Gems/2.0.0/gems/mysql2-0.3.16/lib/mysql2/mysql2.bundle, 9): Library not loaded: libmysqlclient.18.dylib

解决办法：

MYSQL=/usr/local/mysql/bin
export PATH=$PATH:$MYSQL
export DYLD_LIBRARY_PATH=/usr/local/mysql/lib:$DYLD_LIBRARY_PATH

重新执行 bin/rake db:migrate 即可。