Fantastic question ... but just 1 point for this? I am a bit surprised 🙂
As some of you have noted - I missed the Union All too. But where I got stumped was the IN Clause having column names. I swear I had not seen this before and this led me to believe the query is going to error out. I was cool with the Truncate participating in a transaction. I knew that once rolled back the data will be restored to the original state. But the IN clause did me in!
Overall - very craftily created question and something which tested agility and sharpness.