See: Derek’s Rantings and Musings: MySQL Licensing Practices, Again
MySQL has had for a long time now a confusing license for their database software. The database is released under the GPL which means it is free software. But according to the MySQL docs, if you are producing any sort of commercial software or application, you cannot use MySQL unless you purchase a Commercial License. This isn’t what the GPL says. The GPL allows you to do whatever you want with the software without restriction, the only provision is if you modify the source code that is licensed under the GPL you have to release those modifications back to the community. Running a database does not meet the requirements for source code modification.
- If you distribute a proprietary application in any way, and you are not licensing and distributing your source code under GPL, you need to purchase a commercial license of MySQL
- If you are unsure, we recommend that you buy our cost effective commercial licenses. That is the safest solution. Licensing questions can submitted online for our advice, and we encourage you to refer to the Free Software Foundation or a lawyer as appropriate.