Combine multiple aggregations in one query

In the last three exercises, we walked through the ROLLUP, CUBE, and GROUPING SETS grouping operators. Of these three, GROUPING SETS is the most customizable, allowing you to build out exactly the levels of aggregation you want. GROUPING SETS makes no assumptions about hierarchy (unlike ROLLUP) and can remain manageable with a good number of columns (unlike CUBE).

In this exercise, we want to test several conjectures with our data: