TFPExprNode.UpdateAggregate procedure

Declaration

procedure UpdateAggregate; virtual

Description

The UpdateAggregate virtual method updates the aggregate calculation state for nodes that participate in aggregate operations. It is called for each data row or iteration during aggregate processing to incorporate new values into the ongoing calculation.

For most expression nodes, this method does nothing (default implementation). Nodes representing aggregate functions override this method to update their running totals, counts, or other aggregate state based on the current data values.

The UpdateAggregate method works in conjunction with InitAggregate to implement the aggregate processing cycle.