This was quite a tough one.
Learned a fair bit about the origin of the MERGE statement from this.
Took a fair amount of thinking and digging to get it, though.
I think the main reason for the poor score rate is that the SQL ANSI:2003 definitions are not readily available.
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Space, the final frontier? not any more...
All limits henceforth are self-imposed.
“libera tute vulgaris ex”