SUM Aggregate Function

This function calculates the arithmetic sum of all entries in the field value selection.

You can only indicate expressions containing a numerical value as a function parameter.

If the fields do not contain a numerical value, then using the SUM function will produce an error. If the field can contain numerical values (has compound data type), then you can apply this function to the field. But if there is a non-numerical value among the field values (besides NULL), then an error will occur.

See also: Aggregate Functions