Thank you 🙂

Very cool approach!

Unfortunately, time was a worry, so I have re-written my code in to a while loop, and am inserting row-by-row.

While inside the loop, I can query the table I am inserting in to (To stay with the abstraction, I can find the sum of all January values as they are readily query-able in the table I am inserting in to). Not my first choice.

Hope I can find the time to fit your approach to the solution in to my code and measure the performance.

Sadly, the actual problem is a great deal more complex than the abstracted problem.

Thanks again 🙂