You'll need to use one method or another to "mark" the records with duplicate values by putting a value in a "mark" field. then you have a value a portal filter can exclude.
Here's one method:
Give each record in this portal a unqiue serial number in a serial number field.
Open Manage | Database | Relationships
Select the table occurrence for your portal and use the duplicate button (two green plus signs) to make a duplicate of this table occurrence.
Use it to define this relationship:
PortalTable::ColorField = PortalTable 2::ColorField
Now define a calculation field, cMinID, in this table as: Min ( PortalTable 2::serialNumberField )
Now this portal filter will drop out duplicates:
IsEmpty ( PortalTable::cMinID ) or PortalTable::cMinID = PortalTable::SerialNumberField
This should display all records that do not have a duplicate color ( IsEmpty function) or which are the record of a set of duplicates with the smallest serial number (Current serial number matches minimum value with same color).
Thanks for the really swift answer PhilModJunk !
But I'm afraid that I didn't give you enough information. The records on the PortalTable already have unique serial numbers and the colours are not duplicated in that table. They appear multiple times in the portal because the Portal TO is 4th in line from the originating TO. So the portal looks like this:
And I want it to show:
Your elegant answer doesn't seem to help in this case. I'm hoping you may have another answer now that I have been a little clearer !
Again many thanks.
Please post a screen shot of the Relationship Graph or use text to document all the relationships.
Apologies, PhilModJunk ! It works beautifully !