gem install mysql

generates this errors:

ruby extconf.rb install mysql
checking for mysql_query() in mysqlclient.lib... no
hecking for main() in m.lib... yes
checking for mysql_query() in mysqlclient.lib... no
checking for main() in z.lib... no
checking for mysql_query() in mysqlclient.lib... no
checking for main() in socket.lib... no
checking for mysql_query() in mysqlclient.lib... no
checking for main() in nsl.lib... no
checking for mysql_query() in mysqlclient.lib... no

Both in Linux and in Windows.

Any idea?

Thanks in advance. JC