我的环境是centos7  ruby rails nodejs 都已经安装好;使用rails s 启动服务器,报下面这个错
Specified 'mysql2' for database adapter, but the gem is not loaded. Add `gem 'mysql2'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).
尝试安装mysql,但是centos中已经将mysql改为使用mariadb,所以始终不能解决这个