Hi Paul,

I guess this comes down to the guts of a Foriegn Key. What you are saying in your design is that you don't want any records in the GIS_Data table with an invalid ParcelID ( validity meaning that it exists in the Field_Data table ).

So the question is... for those records in GIS_Data that have a ParcelID not residing in Field_Data, what to do with them if they are invalid? And the answer to that is either to enter corresponding ParcelID's into Field_Data, Update invalid ParcelID's to valid ParcelID's in GIS_Data, or set them to NULL.

If the assumption above is correct, you must scrub these records prior to creating the Foriegn Key. Otherwise, the Foriegn Key cannot be created.

Is it true that Field_Data is the parent, and GIS_Data is the child?