Re: One to One relationships

In message <46e627da.0305060738.325caa00_at_posting.google.com>, AK <ak_tiredofspam_at_yahoo.com> writes
>> > Are you sure that patients only have one chart forever? Suppose a
>> > patient is discharged and then readmitted for an unrelated illness.
>> > Don't they then get a new chart?
>>
>>
>> I suppose terminology may vary. I'm using the word "chart" in the same way
>> as "medical record": the collection of a patient's history and statistics.
>
>I would suggest using "DNA records" rather than "medical chart".
>Any individual's genome isn't likely to change, is it?

Yes, I'm afraid it is. Or at least if you checked one person's DNA twice you would quite possibly get two different sequences. It's not uncommon for different cells in the same person to have different slightly DNA.

In general there isn't a good natural key to identify people, that's why most databases use various surrogates (like SSN.) I've proposed a natural key for people; the precise latitude, longitude, altitude and time of their birth. I don't claim that it's a practical system.

-- 
Bernard Peek
bap_at_shrdlu.com
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