First, I'll say this, Relational databases are super powerful and extremely valuable in today's world and while no-sql is really awesome too relational won't go

First, I'll say this, Relational databases are super powerful and extremely valuable in today's world and while no-sql is really awesome too relational won't go anywhere so it is a very valuable skill set to have. As for learning relational databases. First, research some books on Amazon and look at the reviews, because there just are so many good books on them. In general, remember that even within relational databases there are different design guidelines for OLTP (transaction systems think ecommerce) and OLAP (reporting, analytics) etc. IMO, for now, stick with OLTP (transactions based) books and systems. Outside of reading some books, also checkout stack overflow and other sites to get examples of good schema's and bad schema's. And review as many schema's as possible so you get a feel for what works and what doesn't. I look at a ton of schema's in consulting and can tell people problems they are having before they have even told me anything about their issues because it is obvious from their data schema. It doesn't necessarily mean their schema is a bad design, just that all of them have tradeoffs and the best way to learn is to see real schema's and datasets. Also, search for "relational database schema examples" in google image (without the quotes of course), and look at some of the image samples that come up. This will also give you a better feel for how the ER notation or UML notations work. You'll figure them out they aren't that hard. It really is a huge subject, so hunt around for some online training and then ask people for recommendations after you see a few to see if anyone can give you specific feedback on them.