>Looks good for the basics, but as some other folks mentioned here, it would benefit from some articles about design, and even more importantly, rationale.

I agree about rationale, but probably in a different way. For a great many people, especially in the "data analyst camp" (i.e., people coming from finance/consulting background with mind-blowing Excel skills), SQL is not something they want to learn in the vacuum but more like necessary evil. For them, it's hugely valuable to learn how and why SQL can be useful.

http://blog.treasuredata.com/2014/12/05/learn-sql-by-calcula... is my humble attempt to address that issue, and it seems to have resonated well with the data analyst type folks.

Just offering a non-programmer's perspective.