MySQL идет под двойным лицензированием: GNU General Public License или коммерческая лицензия
http://ru.wikipedia.org/wiki/MySQL#.D0.9B.D0.B8.D1.86.D0.B5.D0.BD.D0.B7.D0.B8.D1.80.D0.BE.D0.B2.D0.B0.D0.BD.D0.B8.D0.B5

Не совсем понятно, коммерческое лицензирование может использовать только Oracle(SUN) владелец MySQL или любая фирма?
Если я хочу сделать модифицированную версию MySQL, платную и без открытых исходных кодов, возможно ли это? И нужно ли будет платить какие-то отчисления Oracle'у?

kdvнужно не на википедии читать, а прямо на сайте mysql:
http://www.mysql.com/about/legal/licensing/oem/

в частности, там написано
Q6: What is Oracle's commercial license for MySQL software?
A: Oracle offers a commercial license for all of its MySQL software that is embedded in or bundled with another application. The commercial license allows OEMs, ISVs and VARs to distribute commercial binaries of MySQL software with their own commercial software without subjecting that software to the GPL and its requirement to distribute source code.
Слегка размыто написано.
Т.е. изменять и продавать модифицированную MySQL я смогу только с выплатой Ораклу стоимости исходной(не модифицированной) лицензии MySQL для каждой проданной мною копии?

Вот что ответили:
авторMany thanks for your prompt response and details provided. Since MySQL is fully integrated within your application, yet end users have access to it, it seems the Application Specific Full Use Distribution Agreement would be a good suit for you.
The discount on orders resold under an Application Specific Distribution Agreement is 60% off the Oracle/MySQL price list; to qualify for such discount your company must be a member of the Oracle Partner Network. . Since you have previously mentioned MyISAM and InnoDB as the storage engines, I have summarized below how would the commercials line up both for MySQL Classic Edition and MySQL Standard Edition.

MySQL Classic Edition
List price per <4 sockets $1.800,-
60% ASFU discount $1.080,-
Price per <4 sockets $ 720,-
19% support $ 136,8-
Total price per <4sockets $ 856,8-


MySQL Standard Edition
List price per <4 sockets $6.000,-
60% ASFU discount $3.600,-
Price per <4 sockets $2.400,-
19% support $ 456,-
Total price per <4sockets $ 2.856,-

For additional details on MySQL technical details or compatibility, please check the MySQL website as well. Please let me know what type of information should I address further on; are you interested particularly in aspects of the distribution, terms for reselling, reporting the license usage? There are many aspects included in the distribution agreement itself, yet I need your input to be able to give out exactly what interests you.

I am looking forward to hearing back from you.

Т.е. как я понимаю если я продаю модифицированную MySQL, то должен платить Ораклу стоимость лицензии с возможностью 60% скидки. Плюс (0.4*0.19*100%)=7,6% за тех. поддержку.
Посчитали они мне как я понимаю на сервер с 1 или 2 сокетами двух редакций.