Subject RE: [ib-support] One-to-one relationship
Author Nico Callewaert
Good morning Helen,

Thanks for your answer, very usefull tips, I will keep it very close in my
mind, :-)



-----Oorspronkelijk bericht-----
Van: Helen Borrie [mailto:helebor@...]
Verzonden: woensdag 16 mei 2001 8:43
Onderwerp: Re: [ib-support] One-to-one relationship

At 07:50 AM 16-05-01 +0200, you wrote:
>Hi list,
> Can someone explain to me what is the advantage of a one-to-one
>relationship ? I don't see any advantage on it, because a single record
>the first table is related to only one record in the second table, so why
>don't put it all in one table then ?

I find optional 1:1 relationships useful for situations where I want to
"mix and match" packets of information without needed to have horrendously
wide rows potentially carrying a lot of "empty" columns, as the master to
master-detail relationships.
For a simple example, in a medical application, I might have a "person"
which carries with it some common attributes but also large packets of data
which apply to some persons (e.g. medical history applies to patients
whereas availability for a duty roster applies to doctors and nurses). I
want to store names and some other details about all persons but I don't
usually store medical history for doctors and nurses or roster availability
for patients.

If a person exists, then s/he will always have one or more Address records;
but the 1:1 allows me to store the optional (or conditional) info only if it
is appropriate.


All for Open and Open for All
InterBase Developer Initiative ยท

To unsubscribe from this group, send an email to:

Your use of Yahoo! Groups is subject to