Assume a standard server-side Web application. Database, backend, frontend. It's basic knowledge that one should check the licences of the libraries used before deciding on the license for the final product. For example, if there is a GPL library used in the backend, the whole thing has to be made GPL.

But my question is: if the application runs on a database management system with a copyleft license, does this make the whole application copyleft? On the other hand, if the application runs on a closed source DBMS like Microsoft SQL server, does this mean that making the whole application open source is impossible, because it would be required of the authors to also give the Microsoft SQL server along with the rest of the code?

If it depends on how exactly the connection to the database is made, or how the product is distributed (e.g. does it have an installation file which installs a DBMS automatically), then what condition is important for the final judgment?

2 Answers 2


The question is a bit hard to answer directly. A software project can have both open source and closed source requirements and still be an open source project. The trick is, only the files that are open source can be distributed and modified. Other programs that are required for the project can be included with permission or simply not included with the source at all. If a project has dependencies that cannot be included with source code, it may just be part of the environment setup that must be taken on by the one who is using said package.

In short, the Microsoft database will not make the rest of the projected any less open source.


It is generally understood that using another program generates no derivate work (in difference to linking there it is controversial). As far as I know nobody so far has claimed, that using a database creates a derivate work. Even more, if the interface is an standard used by different programs. If you stick only to standard-SQL, you could replace the Database in the installation without rewriting the program.

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