Create a new Ruby on Rails application using MySQL instead of SQLite

Normally, you would create a new Rails app using

rails ProjectName

To use MySQL, use

rails new ProjectName -d mysql

If you already have a rails project, change the adapter in the config/database.yml file to mysql and make sure you specify a valid username and password, and optionally, a socket:

development:
  adapter: mysql2
  database: db_name_dev
  username: koploper
  password:
  host: localhost
  socket: /tmp/mysql.sock

Next, make sure you edit your Gemfile to include the mysql2 or activerecord-jdbcmysql-adapter (if using jruby).