Hello,
I have another question concerning the semantics of AQL queries:
In the documentation there are queries of the form
SELECT a/data[at0001]/items[at0004]/value
FROM EHR e CONTAINS COMPOSITION a[openEHR-EHR-COMPOSITION.encounter.v1]
WHERE b/data[at0001]/items[at0004]/value/value >= 140
What ensures that the identified path in the SELECT section references
the same data instances that are contrained with the same identified
path in the WHERE section ? It could be argued that there is only one
"data[at0001]" in "b" and only one "items[at0004]" in "a/data[at0001]"
and so on. But is this already the full explanation for the expression
to be unambiguous ? The aliases used in queries (e.g. "a") ensures that
a reference to an alias definitely means the same instance. Looking at
queries like the one above let assume that aliases are only syntactic
sugar and are not functionally needed. Is this correct ?
Greetings
Georg
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Dipl.-Inf. Georg Fette Raum: B001
Universität Würzburg Tel.: +49-(0)931-31-85516
Am Hubland Fax.: +49-(0)931-31-86732
97074 Würzburg mail: georg.fe...@uni-wuerzburg.de
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