Transformation on DB: Filter row. How to filter records with max value in a colum grouped by another column.

[Veronica Nerozzi]

I would like to apply a filter row to select only records with the max value on the field "ID1" for each value in the column "ID2".

I have tried to insert a filter row with the formula: max([iD1]) OVER ([iD2])

but it returns me an errore saying "incorrect expression type 'Real'". The expression must have type 'boolean'"

How can I do?

Thanks.

[Gaia Paolini]

You need to define it as:

[iD1] = max([iD1]) OVER ([iD2])

A filter is a Boolean expression that filters in values that are returned as True. In this case, all values of [iD1] that are equal to their maximum values over [iD2]. So the expression you defined is a 'mask' that is applied by testing every row to check it is True or False.