Hi Rob, you can wrap '$s/timeOfDay' with a call to function 'zero-or-one()' or 'exactly-one()' (depending on what you know about your data). Then it will check at runtime (instead of at compile time) for the correctness of your query. Regards, Jan On Mar 12, 2011, at 20:10, Rob Fynes wrote:
Hello,
I'm trying to produce a sorted list of results with MonetDB/XQuery using 'order by', with a query that goes something like this:
for $cname in pf:collections()/text() return if (local:is-date-between($cname, **start_date_here**, **end_date_here**)) then for $s in pf:collection($cname)//Dublin/stations[time/hour=13 and time/minute>=22 and time/minute<=25] order by $s/timeOfDay return $s else ()
...the 'is-date-between' is just some custom function to check if the $cname (collection names are dates) is between the start and end dates supplied to the function. However, the problem is with the nested for loop. I want each $s that satisfies the XPath expression to be returned, but ordered by $s/timeOfDay.
When I submit this query, I get the following error: ERROR = !type error: [err:XPTY0004] Orderspec requires at most one atomic item (given: string*).
I've tried a number of variations on this, but the error is always the same. If I remove the order by clause, the results will return correctly, but in the unsorted order that they appear in the database.
I'm still a beginner with XQuery, so I'm unsure where I'm going wrong, and documentation and tutorials have been unhelpful so far. Any help is appreciated!
Regards, -Rob ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d__________________________________________... MonetDB-users mailing list MonetDB-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/monetdb-users
-- Jan Rittinger Lehrstuhl Datenbanken und Informationssysteme Wilhelm-Schickard-Institut für Informatik Eberhard-Karls-Universität Tübingen http://www-db.informatik.uni-tuebingen.de/team/rittinger