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Broken exercise requiring a subquery #255
Hi folks. Just noting this here because it was a major trap in the lesson.
is broken. The answer requires a subquery:
And we never teach the idea of subqueries in the lesson. I riffed on this because it helped flow into the VIEWs needed by my edits to the capstone, but I recommend that this exercise be cut, because it's a trap for unwary instructors.
(Basically, because order by runs on the output rows, not the input rows, we need to sort the input data before we hit the aggregation step.)
Just dropping in post-workshop feedback, because I don't have time to edit this in properly to the lesson, and I think it'd introduce way too much cognitive load.
referenced this issue
Jul 6, 2018
I think having summative exercises here is a good thing. And this teaches pivoting with group_concat. If it's just "Hey I can use more aggregation methods, and this one is called group_concat" then I think it works well. So both routes work. Maybe copy this one to one of the final exercises with discussion of subqueries in a todo and leave a non-ordered version here?