http://sqlbolt.com/ Free; and the real deal: jumps to table JOINS relatively rapidly with some real head-scratchers, but a LOT of interactive support, so you can sort of "play" your way toward a solution and see the results as you go.
I've been looking, a lot, into SQL learning resources, and many ancillary things. I've bought books; they have been putting me to sleep.
I've looked at on-line Coursera & other courses. I have bought a few, but mostly find they -- again -- put me to sleep...or alternately start too hard with things like needing to master a new editor or other new tools as a sort of "prerequisite".
And I've looked at a lot of "free" or partially free step-by-step tutorials. (And a few too many articles).
Some of the tutorials have been pretty good, but mostly they either are (1) too constrained; e.g., they teach SQL in the context of embedding it in a program (2) too easy (see #1) or (3) too hard (often with a lot of technical verbiage or some other thing that puts me off or delays my getting started on learning SQL itself… Or (4) pacing is okay, but they course cuts off after a fairly light intro.
Anyway, I've looked at dozens of resources and, generally, not caught the "middle path" I needed. This one is way different. As I said, it launches into JOINs unusually quickly, but not so quickly that I can't follow. And then it drops back, from time to time, to single tables to introduce new aspects of SQL , and then, periodically, draws on *previous* material to reinforce learning.
It goes to like 19 lessons (I'm currently at #11 after maybe 4 hours). I've peaked ahead, and there are additional, even trickier things planned to be turned into additional course material (e.g., subroutines, which are necessary for some more complicated things were results of different queries into "views" (sub-tables, or whatever they are called) are, in turn, JOINED again.
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