I would honestly invest it in a Java course, because I want to learn how to develop apps for Andoid. I have the basics of Java, I just need to learn how to connect the dots and how to write high quality code. Once I get good at Java or any other programming language, it's way easier to get involved in startups rather than having no technical background.
I don't know SQL, but some of my friends work with databases pretty easily. They tell that it's relatively easy to master, especially if you have some basic knowledge of programming.I'd go with something like this. Invest in something that would be good for a resume, real life, a job, etc. I've always wanted to look into SQL since I do know some java and web design and stuff so that would help balance me out with more skills.