ok, but what if there is no ?s with "Emri" and such a Class1 property? I mean, check your data.

Check the all "entities" with "Emri" as object, then check if any of those has the property Class1. I bet there is exactly none

On 01.04.21 09:08, emri mbiemri wrote:
Hello,

Sorry for not being more specific.
I am trying to get all the ?s and ?p that has for instance "Emri" as object.
Then I want to use the above value of ?s, change the value of the predicate to 
<http://www.w3.org/TR/html4/Class1> and get all the objects with that match.

The problem is that when I query just
?s ?p ?attr .
                FILTER regex(?attr , "Emri").

-----I get the three results, one of them is:
        
_:b0
        
<http://www.w3.org/TR/html4/Name>
        
"Emri"

----------------
When I query just for:

  _:b0 <http://www.w3.org/TR/html4/Class1> ?class .

----I get many objects as result.

But, then I try this:

                 ?s ?p ?attr .
                 FILTER regex(?attr , "Emri") .
                 ?s <http://www.w3.org/TR/html4/Class1> ?class .

then I get no matches? Is there maybe because there are three subjects returned 
from the first query(?s ?p ?attr .), or can I not change the value of the 
predicate on the second query after it has been initialized from the first one.

Thanks a lot for your help.









On 2021/04/01 05:57:41, Lorenz Buehmann <[email protected]> 
wrote:
without showing the data impossible to help, sorry. I mean, in the end
the query has to match the data, but we only know the query know - so
how can we help here?

One possible error is the triple pattern

?s <http://www.w3.org/TR/html4/Class1> ?class .


what is the idea behind this? Is there really a property <Class1> in the
data? If not and if you want to get an instance of the Class <Class1>
you have to use

?s a <http://www.w3.org/TR/html4/Class1> .

On 31.03.21 16:12, emri mbiemri wrote:
Dear all,

I am trying to query something from an RDF/XML file with SPARQL but when I try 
queries like this:

SELECT DISTINCT ?class
WHERE {
?s ?p ?attr .
                  FILTER regex(?attr , "Emri") .
                ?s <http://www.w3.org/TR/html4/Class1> ?class .

it should after the FILTER command initialize ?s = _:b0 , but it doesn't?

Hope for any support.

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