For our purposes, we now know how to create, insert, update and delete data in tables. We've also touched on proper db structure, though really the best way to figure this out is to do it so it makes sense. Once you've built a poor database structure or two (or worked with someone else's poorly-implemented database) you'll get an appreciation of the importance of building your db in a scalable, manageable way. As with C#, only practice will make you truly adept.
This tutorial ends the current section on SQL. Next we'll dive back into some C#.