Group By Fields
Use group by fields to define how to group data for aggregate expressions.
The result of an aggregate expression varies based on the group by fields that you configure. When you configure a group by field, the Mapping Configuration task groups rows with the same data in the field. The task performs aggregate calculations on each group and writes the result to the last row in the group.
For example, when you group by the ITEM field for the following expression, the task calculates the quantity of items sold for each item: SUM( QUANTITY ).
If you use the same expression without a group by field, the task finds the total quantity of all items sold.
When you select more than one group by field, the task creates a group for each unique combination of data in the group by fields.
Configure group by fields on the Group By tab of the Properties panel.