Aggregating a calculated field in TClientDataset

Question

Is it possible to add an aggregate field over a calculated field?

Suppose there is a cds with following fields:

• ID(autoincrement)
• Name(string)
• Price(float)
• Quantity(integer)
• Total(integer) - calculated field - Price * Quantity

and I want to add an agregate to get the sum of Total column. Is it possible?

Answer 1

Yes, that is possible if you change the calculated field to an InternalCalc field. The calculation is still done in the OnCalcFields event, but you have to check the state for InternalCalc when you make the calculation for that field.