SQL database usage in commercial projects

Question

I am planning to start a commercial web project (like e.g. facebook) which requires a database.

I've read through all the licenses and FAQ's of MySQL, PostgreSQL and HSQLDB but I am still not certain if I need to purchase a license (commercial type) or have to publish the source code of my web project (open source license) since I am not a lawyer.

My Question is: Can I use any of the databases mentioned above for my commercial project without having to purchase a commercial license or publish my source?

If not, is there a database out there which I could use?

Answer 1

You can use MySQL and PostgreSQL commercially without any sort of purchase. You can purchase support agreements from them, if you need it.

You would not be required to publish your source code simply because you're using an open source database. Only if your project was a modification of the database engine would you need to provide the source.

edit: Per the comment by Pekka above, I realize that I was assuming this was a web site based project with a server-side database engine. If this is not the case, my answer could be misleading.

Answer 2

I contacted the mysql guys and they said that using MySQL as described in my initial post is free of charge:

Certainly during the development phase there is no requirement to purchase a license as you can use the Community Server for that, however it would make sense that once you went live you would purchase MySQL Enterprise to ensure you had access to the most stable versions and support. More information can be found at:

http://www.mysql.com/about/legal/licensing/oem/

Community Server is released under the GNU General Public License Version 2 (also known as the GPLv2). This can be found at http://www.gnu.org/licenses/old-licenses/gpl-2.0.html

Provided your use of MySQL Community Server complies with the GPLv2 then you are free to use it. If you are in any doubt, then it is worth looking at Enterprise.

I also asked if I had to release/publish my code under a open source license if I used the community server. This is the answer I got:

I am not a lawyer, so please take this into account. Also you probably should be talking to the sales staff on what you can and cannot do, you can get their details from the contact pages on www.mysql.com. However as I understand the GPL unless you are distributing MySQL with your code you do not need to release your code under the GPL. If, however, you do distribute MySQL then you either need an OEM/ISV license or your code must be under the GPL, or one of the other Open Source licenses covered in the FOSS exceptions listed in the FAQ page I gave you.