sum method
Sums a numeric field over the current flat dataset view.
Null values are skipped. Empty views and all-null fields return FdcDecimal.zero. Integer and decimal fields are accumulated as FdcDecimal to avoid floating-point drift.
Implementation
FdcDecimal sum(String fieldName) =>
_dataSet._aggregateCached(fieldName, FdcAggregate.sum) as FdcDecimal;