We want to restrict the ability to add a value in a field, if that value is already in the field.
i.e. we want to replicate the way Appsheet will restrict duplicate values in a “key” field
But, we use a different “key field”.
I tried making this other field also a"key", but after saving it was deselected. So appears can only have 1 key.
I know IF and COUNT should be able to be used, but not sure how to…