I'm on mobile, so maybe I'm missing something, but I don't understand how youbare even supposed to get started without knowing SQL. If this is supposed to teach SQL then there needs to be some tutorial to guide the way.
There's also plenty of ways to teach. Some methods assume a basic level of the concepts involved, but by continuing, you'll be exposed to new concepts that level up those skillz. Just like how arithmetic comes before algebra comes before trig comes before calculus.