Hi Paul,

> You define the PKs as a non-nullable datatype - like you already do.
> You define the FKs as the same datatype, but nullable. For instance:

[...]

Even when I define the FKs as nullable, I get an error that the FK
may not be NULL.

The only way not to get the error was to define it as
ON DELETE SET NULL, but I want my FKs to prevent deletes
of the master rows.

Helen's last reply describes a good workaround for my problem.

Anyway, thanks for your help.


Christian