Re: One to One relationships

I use a one to one relationship to define sub-categories of items. Whether or not this is correct, I don't konw. One of the best examples I can think of comes from the aircraft parts industry. All parts have certain characteristics in common (partnumber, serialnumber, qty, etc.) only certain parts have other characteristics (time limiters). I store all parts in the inventory table, and life-limited parts join in a one to one relationship to a life-limited parts table for the extra values that describe them.

This arrangement works well in practice. I also prevents the inventory table from having characteristics that would be null for most parts(indicating unknown) or have to have an entry indicating "not applicable". Received on Thu Apr 24 2003 - 16:45:47 CEST