Iterator ("X") functions: SUMX

- [Instructor] All right, we're savin' some of…the best stuff for last,…'cause up now, we've got iterator, or X functions.…And the thing about these iterator functions…is that they allow you to loop through…the same calculation or expression…on every single row of a table…and then apply some sort of aggregation…to the results.…So you can take the sum, the max, the min,…the count, the average, any kind of aggregation.…So if you've ever written a sum product function…in Excel, then you already know how these work.…Because the sum product takes a product…on each row of the data set…and then sums the answers up.…

The difference is that instead of just…taking a sum, like a sumx,…you've got several other options as well.…So you've got a countx version, an averagex,…a rankx, a maxx and a minx.…And each of these applies a different…type of aggregation to the results derived…by the expression.…So the first argument in the syntax…is just a reference to the table.…And this is the table in which…the expression will be evaluated.…