gem install mysql failing with checking for mysql_query() in -lmysqlclient… no

Aside

If you run into an error similar to the follow while attempting to install mysql gem on OSX Lion

sudo gem install -V mysql -v '2.8.1'
GET http://rubygems.org/specs.4.8.gz
302 Moved Temporarily
-- snipped --
Installing gem mysql-2.8.1
/Library/Ruby/Gems/1.8/gems/mysql-2.8.1/COPYING
-- snipped --
Building native extensions.  This could take a while...
ERROR:  Error installing mysql:
	ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/
1.8/usr/bin/ruby extconf.rb
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lmygcc... no
checking for mysql_query() in -lmysqlclient... 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.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/System/Library/Frameworks/Ruby.framework/
              Versions/1.8/usr/bin/ruby
	--with-mysql-config
	--without-mysql-config
	--with-mysql-dir
	--without-mysql-dir
	--with-mysql-include
	--without-mysql-include=${mysql-dir}/include
	--with-mysql-lib
	--without-mysql-lib=${mysql-dir}/lib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-mlib
	--without-mlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-zlib
	--without-zlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-socketlib
	--without-socketlib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-nsllib
	--without-nsllib
	--with-mysqlclientlib
	--without-mysqlclientlib
	--with-mygcclib
	--without-mygcclib
	--with-mysqlclientlib
	--without-mysqlclientlib

Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/mysql-2.8.1 for inspection.
Results logged to /Library/Ruby/Gems/1.8/gems/mysql-2.8.1/ext/mysql_api/gem_make.out

You can fix it passing along the mysql_config5 param to the command. On Lion, if you installed mysql by using the command sudo /opt/local/bin/port install mysql5-server or something similar the command to install the gem is

sudo gem install -V -v '2.8.1' mysql -- --with-mysql-config=/opt/local/bin/mysql_config5