Re: My honours project - databases using dynamically attached entity-properties - Mailing list pgsql-hackers

Gregory Stark wrote:
> "David Fetter" <david@fetter.org> writes:
> 
>> CREATE TABLE symptom (
>>     symptom_id SERIAL PRIMARY KEY, /* See above. */
>>     ...
>> );
>>
>> CREATE TABLE patient_presents_with (
>>     patient_id INTEGER NOT NULL REFERENCES patient(patient_id),
>>     symptom_id INTEGER NOT NULL REFERENCES symptom(symptom_id),
>>     UNIQUE(patient_id, symptom_id)
>> );
> 
> I'm just glad I don't have your doctor. I hope mine doesn't think symptoms are
> all boolean values.

With a unique across (patient_id,symptom_id) you could have a single
patient with as many unique symptoms as could be listed.



Joshua D. Drake




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