Ruby使用MySQL問題記錄

1.使用gem安裝mysql2的時候提示以下錯誤extconf.rb:2:in `require': no such file to load -- mkmf (LoadError) from extconf.rb:2

Building native extensions.  This could take a while...

ERROR:  Error installing mysql2:

ERROR: Failed to build gem native extension.

/usr/bin/ruby1.8 extconf.rb

extconf.rb:2:in `require': no such file to load -- mkmf (LoadError)

from extconf.rb:2

原因：缺少mkmf，mkmf.rb is part of the ruby1.8-dev package。

解決辦法：sudo apt-get install ruby1.8-dev

2.WARNING: This version of mysql2 (0.3.2) doesn't ship with the ActiveRecord adapter bundled anymore as it's now part of Rails 3.1

WARNING: Please use the 0.2.x releases if you plan on using it in Rails <= 3.0.x

原因：rails版本小於3.1，mysql2版本大於0.3，造成版本不相容；

解決辦法：在Gemfile裡面把mysql2的版本調低一點設成gem 'mysql2', '< 0.3'就可以了，或者直接gem install mysql2 -v 0.2.7安裝一個確切的版本，再在gemfile中將mysql2設成該版本；或者把rails升級到3.1以上版本，該方法未驗證。

3.Installing mysql2 (0.3.6) D:/develop/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/defaults/operating_system.rb:9:in `block in <t

op (required)>': The 'mysql2' native gem requires installed build tools. (Gem::InstallError)

原因：缺少devkit，無法安裝mysql2；

解決辦法：去'http://rubyinstaller.org/downloads 下載devkit，然後按照http://github.com/oneclick/rubyinstaller/wiki/Development-Kit 的說明安裝測試，再執行即可。

4.安裝mysql2時報ERROR:Failed to build gem native extension.，具體如下：

Building native extensions.  This could take a while...

ERROR:  Error installing mysql2:

ERROR: Failed to build gem native extension.

google後發現很多人在安裝的時候把mysql自身的參數帶上就可以裝成功，比如帶--with-mysql-lib=${mysqlLibPath}或--with-mysql-dir=${mysqlDir}或--with-mysql-config=${mysqlConfigPath}。都有試過還是一樣，最後從apt中裝了個mysql的開發包libmysqlclient-dev，才從gem上將mysql安裝成功。