升级ror版本

升级rails版本和Gem版本时，先
gem update rails
gem update
然后它会出现mysql的驱动错误的提示如下：

问题： The bundled mysql.rb driver has been removed from Rails 2.2. Please
install the mysql gem and try again: gem install mysql.C:/ruby/lib/
ruby/gems/1.8/gems/mysql-2.7.3-x86-mswin32/ext/mysql.so

答案：
我在电脑上解决成功的方法：gem install mysql 然后直接copy instantrails中的/mysql/bin/libmysql.dll，放进"/ruby/bin"

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感觉这是windows下mysql gem的问题
如果libmysql.dll的版本不对的话（或者mysql安装目录有空格？）
就会出这个错

我的是windows vista, mysql 5.1.30，直接copy mysql/bin/libmysql.dll到ruby/bin不管用，找下面的办法，从instantrails那里找个libmysql.dll放到ruby/bin里面管用了


搜来一个管用的办法：http://www.ruby-forum.com/topic/172179

If you are having problems with MySQL, getting errors like: The
bundled mysql.rb driver has been removed from Rails 2.2. Please
install the mysql gem and try again: gem install mysql.C:/ruby/lib/
ruby/gems/1.8/gems/mysql-2.7.3-x86-mswin32/ext/mysql.so

Here is the solution: 1) First, gem install mysql. If this doesn't
help continue 2) Copy libmysql.dll from InstantRails (see below) to
your mysql directory (C:/mysql/bin/). Restart your computer and it
should be working.

InstantRails libmysql.dll:
http://instantrails.rubyforge.org/svn/trunk/InstantRails-win/InstantRails/mysql/bin/