A difficult chapter with lots of function to help build more complexed sets. The Order-function which order the result in DESC/ASC or BDESC/BASC which means that they don´t care if the result is ordered higher up in the hierarchy. To restore a set to its natural order you use the Hierarchize-function. To retrieve the first or the last in a set, use the TopCount or BottomCount and specify how many you want to show. A filter can be used to filter a set and have similar function like a where-clause. The function NonEmpty can be used if you want to exclude empty tuples from a set. Then there are three functions that can work with the set to compare different sets, “Union” (merge two sets), “Except” (identify what is one set compared to another) and “Intersect” (identify tuples that exist in both compared sets). The “Generate”-function works like a foreach-loop that takes an expression and evaluates that on a collection of sets (do something every iteration). The “Extract”-function can be used to extract member references to form a new distinct combination, good to use when you want to drill down to something and “loose” the previously “higher-level”.
Now i will continue with some aggregations.