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To use a field or column in a function, do one of the following:
Drag it to the Aggregate Functions pane.
Right-click it in the Tables pane and click Aggregate.
The type of aggregation possible depends on the data type of the field. In the Aggregate Functions pane, click the down arrow on the field name and select one of the following:
Avg: The average of all non-null values in the column
Count: The count of all non-null values in the column
Max: The maximum of all non-null values in the column
Min: The minimum of all non-null values in the column
Sum: The sum of all values in the column