AQL queries

Technical (archive)
1

I still think it is unfortunate that none of the existing tools nor
the web based CKM show the appropriate AQL path for each data element.

It is near impossible to manually build

...
WHERE openEHR-EHR-OBSERVATION.blood_pressure.v1/data[at0001]/events[at0006]/data[at0003]/items[at0004]/value/value

= 140

the only way I can do it is to write code to parse the ADL and build
the path but I have nothing to validate that my implementation was
correct

it would be nice to have a set of illustrative AQL queries that one
could validate against.

2

Greg Caulton wrote:

I still think it is unfortunate that none of the existing tools nor
the web based CKM show the appropriate AQL path for each data element.

It is near impossible to manually build

...
WHERE openEHR-EHR-OBSERVATION.blood_pressure.v1/data[at0001]/events[at0006]/data[at0003]/items[at0004]/value/value
  
Currently you can get the paths from the Archetype workbench - path
view. See
http://www.openehr.org/svn/ref_impl_eiffel/TRUNK/apps/doc/adl_workbench_help.htm

- thomas beale

3

Hi Greg,

Thank you for raising your issue.

Sorry that I don't really understand what you want to do? Do you want a path
for an archetype node or do you want to use AQL to retrieve EHR data?

The AQL where clause stated in your previous email is not quite correct. It
should always starts with a variable which is defined in the AQL from
clause, such as:

Select bp

From EHR e CONTAINS Composition anyComposition CONTAINS Observation

bp[openEHR-EHR-OBSERVATION.blood_pressure.v1]
Where
bp/data[at0001]/events[at0006]/data[at0003]/items[at0004]/value/magnitude>=1
40

In this query, anyComposition and bp are variables.
This path "/data[at0001]/events[at0006]/data[at0003]/items[at0004]/value"
points to the systolic element.value - DV_QUANTITY
This path
"/data[at0001]/events[at0006]/data[at0003]/items[at0004]/value/magnitude"
points to the systolic element value magnitude - double.

In future, we do need AQL validations, I agree.

Ocean Template Designer has AQL builder prototype. However, it is only a
prototype, only about three weeks work. However, it can be used to create
simple AQL queries. We are in the process of building a new AQL builder.

AQL specifications is on openEHR wiki. Any comments or criticisms are
welcome.

Cheers,
Chunlan