It does not seem possible to define a VFP database relationship where the child table has "insert restrict" and "nulls allowed" on the foreign key column.

I wish to have a child table INVLIVE where the foreign key column CASE_ID may be null. But if CASE_ID is not null, then it is to be a valid value within the parent CASE table.

When I specify the rule of insert restrict, the generated stored procedure has a line like if seek( lcChildID, pcParentWorkArea) which generates an error of datatype mismatch because lcChildID is NULL. The entire stored procedure does not mention or take into account NULLs.

Is there anyway to modify how VFP generates trigger code besides modifying it after the fact?