Good morning Helen,

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

Greetings,

Nico

-----Oorspronkelijk bericht-----
Van: Helen Borrie [mailto:helebor@...]
Verzonden: woensdag 16 mei 2001 8:43
Aan: ib-support@yahoogroups.com
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

in

>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.

Cheers,
Helen

All for Open and Open for All
InterBase Developer Initiative · http://www.interbase2000.org
_______________________________________________________

To unsubscribe from this group, send an email to:
ib-support-unsubscribe@egroups.com



Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/