Yes – A SQL lecture (or sequence of lectures) is certainly on our TODO list. It still helps when people express that this is something they’re interested in because it may move it in our priority list.
We are teaching a version of this material and, if things go according to our current plan, we would potentially have a SQL lecture sometime in the next 3-4 months. I wish it could be sooner but our collective bandwidth is low right now.
We’ll have to look into the size of the
df2 – We may have changed what is in it which made it a different size.