Working as designed; foreign keys and unique indexes are only valid for the explicit table they point to. You can try making “hard drive” have a one-to-one relationship with “product” instead of inheriting from it. Either give “hard drive” its own PK and add a “Product PK” to the table or have the “hard drive” and “product” tables both use the same primary key (product PK) with a FK between them. David J. |
