There are cases where you would like to perform calculations and segment on aggregated data using subqueries. For example, you might want to count the number of emails each subscriber has opened in the last 2 months or get the value of the highest order for each customer in the last 6 months.
These calculations can be performed with the use of Aggregations.
DESelect provides the option to choose between Count, Sum, Minimum, Maximum, and Average to create an Aggregation on a (filtered) selected field.
More details on how this functionality works can be found below: