I'm just starting out with Ruby (and rails). I did the setup according to <http://ruby.railstutorial.org/ruby-on-rails-tutorial-book#sec:ruby> gems, using `rvm`. I have everything working well with sqlite. 

Now I'd like to try converting things over to MySQL, since that's what I do most of my development with. In my Gemfile I've replaced sqlite with mysql2:

```
group :development, :test do
#  gem 'sqlite3', '1.3.5'
  gem 'mysql2'
  gem 'rspec-rails', '2.9.0'
end

```

But when I try to create the DB for rails in MySQL I get:

```
$ rake db:create --trace
rake aborted!
dlopen(/Users/username/.rvm/gems/ruby-1.9.3-p194@rails3tutorial2ndEd/gems/mysql2-0.3.11/lib/mysql2/mysql2.bundle, 9): Library not loaded: libmysqlclient.18.dylib
  Referenced from: /Users/username/.rvm/gems/ruby-1.9.3-p194@rails3tutorial2ndEd/gems/mysql2-0.3.11/lib/mysql2/mysql2.bundle
  Reason: image not found - /Users/username/.rvm/gems/ruby-1.9.3-p194@rails3tutorial2ndEd/gems/mysql2-0.3.11/lib/mysql2/mysql2.bundle

```

I've seen other postings recommending re-installing MySQL via homebrew (mine was installed via a downloadable DMG), but I'd prefer not to do that as I have several other databases in there already for other non-ruby projects.

I do in fact have the file that Rails is looking for; it's installed in `/usr/local/mysql/lib/libmysqlclient.18.dylib`. What's the best way to tell Rails how to locate it?