Rob,
> Yes. With this you can find all part numbers/supplies which match your
> value, wattage criteria in one table. Or exclude any which have a
> non-null is_replacement_for value.
I understand -- thanks. I have received contradictory advice in a
purely data modeling context. What about the null values that will be
in the properties columns of the part? It would appear to be more
applicable to an employee database where the columns are populated
regardless and the "replacement_for" in the context of our discussion
would be a self-reference to the employee's manager. No?
Thanks again for your help.
-- Gary Chambers