Prevent duplicates in list (virtual column type list)

Hi! Is there a way to prevent duplicates in a virtual column type list? I would like to prevent duplicates just in the current order, (If I already picked apple, I should not add apple again?)

I belive that Order Details column is a reverse-ref (isPartOf property of your Ref set to TRUE). If so;
you can set a valid_if expression in your child table for that [Fruit] column. Please make necessary changes in the expression to fit in your table schema.

            [_THISROW].[Fruit] = [Fruit],
            [_THISROW].[RefColName] = [RefColName]
) = 0

Thanks, I think it will be the solution, but I don’t know where my mistake is. If I understand, It will count Product (fruit) in Orders, but in my Orders table I don’t have a Product Column. :thinking:

Captura de pantalla 2020-06-28 a la(s) 10.29.45

Yeah, It works! thanks

You’re welcome