Question

I have a query on database table structure.
My Patient Details table in a SQL Server 2008 database looks like this:

–PatientId(PK)– –PatientType– –DoctorId(FK)– –DateOfVisit– –PrescriptionId(FK)–

Each patient may visit the hospital multiple times. I need to link all the visits of a patient and show them in a linked way that the admin can navigate with the previous and next visits..

So I think I can do it only by having a record for each visit with a VisitId.

I need to be Careful that the database should not be loaded with unnecessary fields. Also it should not affect the fetching time badly.

I think these are the available ways. Suggest me if any available.

–PatientId(PK)– –PatientType– –DoctorId(FK)– –DateOfVisit– –PrescriptionId(FK)– –VisitId– –PrevVisitId– NextVisitId–

or

having a separate table for Visit as

–VisitId(PK)– -PrevVisitId(FK)– –NextVisitId(FK)–

Apologies if my post is duplicate.. Correct me, redirect me wherever/whenever needed.

Answer 1

So I think I can do it only by having a record for each visit with a
VisitId.

You need a row for each visit. You need a key for each row. The key doesn’t need to be a single id number. I think the very least you need to record for each visit is

create table visits (
  patient_id integer not null, -- references patients (patient_id), not shown
  doctor_id integer not null,  -- references doctors (doctor_id), not shown
  office_visit_start timestamp not null default current_timestamp,
  primary key (patient_id, office_visit_start)
);

insert into visits values (1, 1, '2012-02-01 08:00');
insert into visits values (1, 1, '2012-02-01 15:00');
insert into visits values (1, 1, '2012-03-01 09:33');
insert into visits values (2, 1, '2012-02-01 09:00');

(Exact syntax varies depending on your dbms platform.) You can find the previous and next visits by fairly simple queries–“office_visit_start” will give you the order of a patient’s visits.

Example queries . . .

-- Previous visit for patient # 1 (before 2012-02-01 15:00)
select patient_id, max(office_visit_start)
from visits 
where patient_id = 1
  and office_visit_start < '2012-02-01 15:00'
group by patient_id

-- Next visit for patient # 1 (after 2012-02-01 15:00)
select patient_id, min(office_visit_start)
from visits 
where patient_id = 1
  and office_visit_start > '2012-02-01 15:00'
group by patient_id