For Ruby on Rails, how to "gem install mysql2" after upgrading from Leopard to Snow Leopard?

It always says:

ERROR:  Error installing mysql2:
    ERROR: Failed to build gem native extension.

        /Users/peter/.rvm/rubies/ruby-1.9.2-p180/bin/ruby extconf.rb
checking for rb_thread_blocking_region()... *** 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.

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similar things happen if it is sqlite3:

ERROR:  Error installing sqlite3:
    ERROR: Failed to build gem native extension.

        /Users/peter/.rvm/rubies/ruby-1.9.2-p180/bin/ruby extconf.rb
checking for sqlite3.h... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log 开发者_StackOverflow社区file for more
details.  You may need configuration options.

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Update: at least sqlite3 is building now... that is after I rvm remove 1.9.2-p180 and removing all the 1.9.2, and reinstall by rvm install 1.9.2 and now sqlite3 can be bundle installed, but mysql2 still has problem.

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I installed the 64 bit version of MySQL server and it will bundle install, and then this question helped with the

Library not loaded: libmysqlclient.18.dylib (LoadError)

solution: Library not loaded: libmysqlclient.16.dylib error when trying to run 'rails server' on OS X 10.6 with mysql2 gem