The sources have been downloaded here :
http://www.perl.com/CPAN/modules/by-module/DBD/DBD-mysql-2.9007.tar.gz

AUTHORS
    The current versions of DBD::mSQL and DBD::mysql is almost completely
    written by Jochen Wiedmann (*joe@ispsoft.de*). The first version's
    author was Alligator Descartes(*descarte@symbolstone.org*), who has been
    aided and abetted by Gary Shea, Andreas König and Tim Bunce amongst
    others.

    The Mysql module was originally written by Andreas König
    <koenig@kulturbox.de>. The current version, mainly an emulation layer,
    is from Jochen Wiedmann.

COPYRIGHT
    This module is Copyright (c) 1997-1999 Jochen Wiedmann, with code
    portions Copyright (c)1994-1997 their original authors. This module is
    released under the same license as Perl itself. See the Perl README for
    details.

Check the perl license in /usr/share/doc/perl/copyright.

You can also read the General Public License and the Artistic License
in /usr/share/common-licenses/GPL and /usr/share/common-licenses/Artistic
respectively.