In business we often hear the phrase, “We had a good quarter.” Immediately, we know this means a three month span where sales and profits have been aggregated together for the company. Take a company like Costco that might have $65 billion in total sales during the 4th Quarter (October, November and December). Of course, this total comes not from a single sale of a 65 billon dollar yacht, rather from millions of sales of common items like snacks, drinks, clothes, and light bulbs. We know how to use GROUP BY and SUM to calculate totals and combine similar data. In the case of Costco we group by calendar quarter and then sums on the sales. Although aggregates are commonly used with numbers, they can also be used with spatial land coordinates to assemble them together, much like a jigsaw puzzle. Let us learn about Spatial Unions.