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Database structure


I would like an advise on the following problem :

I have a table of patients.
Each patient can make different biological assessments.
Each assessment is always decomposed into different laboratory tests.
A laboratory test is made of a test number and two values coming from

The schema is :
Assessment(#assessment_nr, #patient_nr, assessment_type, other usefull
values). Assessment_types(assessment_type, labtest_nr) An assessment
is composed of different tests, let's say assessment type 1 is
composed of lab test 1,2,3,5 and assessment type 2 of lab test number
10 to 70.

I have an assessment with 60 different lab tests (always the same). I
have two ways for storing the values :

1 - a table with 120 columns for the two values.
results(#assessment_nr, p10,d10, p11,d11, .....,p70,d70).
where 10 to 70 represents the lab test number.

2 - a table with 60 rows for one assessment :
results(#assessment_nr, labtest_nr, p, d) where p and d are my two

Here comes my question. Which of the two would you choose?

The firsrt solution has the advantage of returning one single row for
one complete assessment. If I have to make statistics, it is easy.
But, if I have to modify the composition of an assessment (which
occurs very rarely), I shall have to use an alter table instruction.
As I have 4 different assessment types, I have to create five
different tables, one per assessment type.

The second solution is normalized and more elegant. But I am
preoccupied by the size of the table. For one assessment, I'll store
60 rows with only two useful integers in it. And you must add the size
of the index. With 25.000 assessments a year, it makes 1.500.000 rows
with only 4 columns amoung them 2 only for the results and 2 for
identification. I would like to store 10 years online, so 15.000.000
rows. What about the size of index ?

Any advise ? I thank you in advance.
Alain Reymond

Jul 19 '05 #1
0 1228

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