Ruby Installing mysql2 (0.2.17) with native extensions Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension

以下のエラーが発生した際の対処方法について説明します。


Installing mysql2 (0.2.17) with native extensions
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension

        C:/Ruby193/bin/ruby.exe extconf.rb
checking for rb_thread_blocking_region()... yes
checking for rb_wait_for_single_fd()... yes
checking for main() in -llibmysql... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

上記のエラーは、MySQLのライブラリが検出できないため発生しているようです。
対処方法としては、gemコマンドにオプションを指定して、MySQL2をインストールします。

C:\Users\yasu\Downloads\dbloete-masquerade-fdf8ef1>subst X:  "C:\Program Files (
x86)\MySQL\MySQL Server 5.5"

C:\Users\yasu\Downloads\dbloete-masquerade-fdf8ef1>gem install mysql2 -v 0.2.17
-- --with-mysql-dir=X: --with-mysql-lib=X:\lib
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
Successfully installed mysql2-0.2.17
1 gem installed
Installing ri documentation for mysql2-0.2.17...
Installing RDoc documentation for mysql2-0.2.17...

C:\Users\yasu\Downloads\dbloete-masquerade-fdf8ef1>subst X: /D

【参考URL】
http://stackoverflow.com/questions/3608287/installing-mysql2-gem-for-rails-3