Is there any reasons why we drop column here? Dropped column case has been tested on table dropped_cols. The generated column problem can be detected without dropping columns on my machine.
We don't really need to, if you check the first patch, we don't have DROP for generated case. I mostly
wanted to make the test a little more interesting, but it also seems to be a little confusing.
Now attaching v2 where we do not drop the columns. I don't have strong preference on
which patch to proceed with, mostly wanted to attach this version to progress faster (in case