I have a validation module in Python that executes an XQuery on an XML document to check if any <Start> times come after <End> times, and return the count of them. The query is as follows:
for $d at $count in ./ty:Detections/Detection
where $d/Start > $d/End
return $count
Now this works fine and good for all cases except when milliseconds are appended to an End time but not a Start time, e.g.:
<Start>2009-02-23T02:53:14Z</Start>
<End>2009-02-23T02:53:14.226Z</End>
This always returns True, even though clearly 14 is less than 14.22.
If I add a single decimal place to the <Start> time here, it works -- but is there any better solution?
Presumably there is no schema binding in effect for the Start and End elements. In that case the query is doing an xs:untypedAtomic comparison, which effectively compares the string values, where "Z" compares greater than ".".
What you want is an xs:dateTime comparison, so you should compare the element values after casting them to that type. The query thus should look like:
for $d at $count in ./ty:Detections/Detection
where xs:dateTime($d/Start) > xs:dateTime($d/End)
return $count