Joshua D. Drake wrote:
Gregory Stark wrote:
"David Fetter" <[EMAIL PROTECTED]> 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.

I think Greg is suggesting that the table needs to be augmented with, say, a severity field.



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