My assumption was that the 'contains
openEHR-EHR-COMPOSITION.encounter.v1' will restrict the result set to
be in this case blood pressure observations that were recorded on an
encounter note (or any document identified as such).
If I make up an archetype called assessment you could have the
following to get blood pressure results from two different document
types - not sure if they intention was for all assessments to be
designated as encounter notes though - perhaps.
SELECT o
FROM
EHR
CONTAINS COMPOSITION c [openEHR-EHR-COMPOSITION.encounter.v1]
CONTAINS OBSERVATION o [openEHR-EHR-OBSERVATION.blood_pressure.v1] AND
CONTAINS COMPOSITION a [openEHR-EHR-COMPOSITION.assessment.v1]
CONTAINS OBSERVATION o2 [openEHR-EHR-OBSERVATION.blood_pressure.v1]
Greg
http://www.patientos.org
On Tue, Feb 24, 2009 at 7:00 AM, <openehr-technical-request at openehr.org>
wrote:
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> ? 1. AQL queries and one-many relationships (John.Ryan-Brown at csiro.au)
> ? 2. OpenEHR'ED (Derek Meyer)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 24 Feb 2009 17:23:00 +1100
> From: <John.Ryan-Brown at csiro.au>
> Subject: AQL queries and one-many relationships
> To: <openehr-technical at openehr.org>
> Message-ID:
> ? ? ? ?<8C3F2174B3FE2B408CB380513186BEC45752819AE6 at
> EXNSW-MBX03.nexus.csiro.au>
>
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>
> Hello. I am currently investigating AQL and would like to know how the
> following queries would be answered by a conformant AQL query engine. I
> understand that the structure of AQL query results are not standardized yet
> in the AQL specifications, so if the spec cannot give a definitive answer
> what would Ocean's AQL query engine implementation do?
>
> 1. ?SELECT
> ? ? ?o/data[at0001]/events[at0031]/data[at0003]/items[at0004]/value AS
> PosturalChangeSystolic,
> ? ? ?o/data[at0001]/events[at1004]/data[at0003]/items[at0004]/value AS
> ParadoxSystolic
> ? ?FROM
> ? ? ?EHR
> ? ? ?CONTAINS COMPOSITION c [openEHR-EHR-COMPOSITION.encounter.v1]
> ? ? ?CONTAINS OBSERVATION o [openEHR-EHR-OBSERVATION.blood_pressure.v1]
> ? ?WHERE
> ? ? ?o/data[at0001]/events[at0031]/data[at0003]/items[at0004]/value/value >=
> 140 OR
> ? ? ?o/data[at0001]/events[at1004]/data[at0003]/items[at0004]/value/value >=
> 140
>
> This query attempts to find all Systolic readings for Paradox and Postural
> Change blood pressure events where the Systolic reading for either is >= 140.
> As there is a one-to-many relationship between a blood pressure observation
> and both Paradox and Postural Change events, how should the query be
> processed? If an observation has three Postural Change events where Systolic
> >= 140, and four such Paradox events, would the query return twelve rows
> (using my relational database thinking). Or would one row be returned, having
> two "lists" (with three and four members respectively) of Systolic readings?
>
>
> 2. ?SELECT o
> ? ?FROM
> ? ? ?EHR
> ? ? ?CONTAINS COMPOSITION c [openEHR-EHR-COMPOSITION.encounter.v1]
> ? ? ?CONTAINS OBSERVATION o [openEHR-EHR-OBSERVATION.blood_pressure.v1]
> ? ?WHERE
> ? ? ?o/data[at0001]/events[at0031]/data[at0003]/items[at0004]/value/value >=
> 140 OR
> ? ? ?o/data[at0001]/events[at1004]/data[at0003]/items[at0004]/value/value >=
> 140
>
> This query is the same as the previous one, except that it returns the whole
> observation. It seems to me that all readings should be returned, regardless
> of their systolic values?
>
>
> 3. ?SELECT o
> ? ?FROM
> ? ? ?EHR
> ? ? ?CONTAINS COMPOSITION c [openEHR-EHR-COMPOSITION.encounter.v1]
> ? ? ?CONTAINS OBSERVATION o [openEHR-EHR-OBSERVATION.blood_pressure.v1]
> ? ?WHERE
> ? ? ?o/data[at0001]/events[at0031]/data[at0003]/items[at0004]/value/value >=
> 140 AND
> ? ? ?o/data[at0001]/events[at1004]/data[at0003]/items[at0004]/value/value >=
> 140
>
> This query is the same as the previous one, except that the OR has been
> changed to an AND. It could be argued that only the Paradox and Postural
> Change events with a Systolic reading >= 140 should be returned, but it could
> also be argued that all readings should be returned, as the whole observation
> has been selected.
>
>
> The problem I have is how to treat queries which have in the WHERE clause a
> path expression that traverses through a 1:n relationship. In trying to think
> through the semantics of such queries, I come up with ambiguities. In a
> relational query (i.e. SQL) the "equivalent" path expression would have to be
> expressed as a join between tables in the FROM clause, thus removing the
> ambiguities.
>
> Am I missing something or are my concerns relevant? If so, how does the
> spec/Ocean implementation address them?
>
> Thanks,
>
> John Ryan-Brown
> The Australian e-Health Research Centre
> CSIRO ICT Centre
> Brisbane
>
