There's two different ways to store Wix Sales Data in Order Data Collections -
One Record for Every Order #
One Record for Every Item in an Order
Both are shown and explained in the Course.
One Record for Every Order
Each Record contains Sales Data for one Order #.
In this organization you can search and datamine the info for any Order by referencing the unique Order #.
One Record for Every Item in Every Order
Each Record represents Sales Data for one Item in every Sales Order.
For an Order with four Items, there's four Records with the same Order # but with Item info about one Item in the Order.
This type of organization can be datamined and sorted by Item Fields, like searching for how many Items of a particular SKU were sold in a time period or in a region of the world.