Errata

Figure 3-2 results are of songs, not of albums. It looks like the query does not define albums in any way. "?albums" can be anything, as far as I can say. At least judging from the results, such as "Back in the Day (Missy Elliot song)".

This album/producer query has been problematic from the start. Quite complex to introduce at the beginning of the book and, as you can see, it's not clear to me whether it is logically sound. I'd suggest "parsing" it--introducing sections of it first, so that it's clear what are the results of "is producer of", and only after that adding complexity. Also, I've been trying to wrap my mind around the metadata used there and how to find what works. For example, "album" is both property and class. The book should perhaps explain what this is and why this is so at this point. At least briefly. Perhaps a simpler example would work here better. Thank you.

Note from the Author or Editor:
Yes, it does list songs instead of albums, so that should be corrected. Other errata have pointed out that the query needs revision anyway because the data model of the queried data has changed, so I will take these suggestions into account when revising it.

replace "some subproperty of" with "some subclass of"

Note from the Author or Editor:
Change as described.

In ex049.rq replace musicalArtist with artist

Note from the Author or Editor:
The schema of the data being queried has been changed and the reader correctly pointed out that the query needs to be adjusted to reflect that change.

In ex048.rq replace musicalArtist with artist

Note from the Author or Editor:
The schema of the data being queried has been changed and the reader correctly pointed out that the query needs to be adjusted to reflect that change.

In ex025.rq replace musicalArtist with artist

Note from the Author or Editor:
The schema of the data being queried has changed, so the query needs to be adjusted as Elio points out.

The Timbaland example in Chapter 1 (Figure 1-3; ex025.rq) uses the DBpedia Ontology property type of "musicalArtist". The query does not return results.

Replacing "musicalArtist" with the property type of "artist" returns results:

SELECT ?album ?artist WHERE {
?album d:producer :Timbaland .
?album d:artist ?artist .
}

Note from the Author or Editor:
Update as shown. https://dbpedia.org/ontology/musicalArtist is still in the DBpedia ontology, but I guess they're phasing it out. (Examples like this will probably use Wikipedia instead of DBpedia anyway in any future versions of the book.)

Hello,

In ex282.rq and ex281.ttl, the rdfs:type property is used while :type does not belong to RDFS but to the RDF ontology.

Thank you,

Note from the Author or Editor:
Change rdfs:type to rdf:type in the 4 places where it occurs on page 163.

The paragraph states that one can run ex007.rq without specifying the ex002.ttl file. However, with Apache Jena 3.13.1-1 on Archlinux, I get the following error:

[heumos@wave LearningSPARQLExamples]$ arq --query ex007.rq
Exception
java.lang.NullPointerException
at org.apache.jena.query.QueryExecutionFactory.make(QueryExecutionFactory.java:615)
at org.apache.jena.query.QueryExecutionFactory.create(QueryExecutionFactory.java:94)
at arq.query.lambda$queryExec$0(query.java:224)
at org.apache.jena.system.Txn.exec(Txn.java:77)
at org.apache.jena.system.Txn.executeRead(Txn.java:115)
at arq.query.queryExec(query.java:222)
at arq.query.exec(query.java:153)
at jena.cmd.CmdMain.mainMethod(CmdMain.java:93)
at jena.cmd.CmdMain.mainRun(CmdMain.java:58)
at jena.cmd.CmdMain.mainRun(CmdMain.java:45)
at arq.arq.main(arq.java:28)

I suspect this might not be the book's fault, but the one of arq. But I don't know for sure.

Note from the Author or Editor:
I reproduced the error with Jena 3.13.1 after getting it to run fine with 3.10.0 and will report the problem to the Jena mailing list.

The example does need revision. In https://lists.apache.org/list.html?users@jena.apache.org see Andy Seaborne's 2019/11/30 22:20:58 response in the thread with a subject of "arq bug?"

ex209.rq does not provide the same results for the third problem as ex207.rq. The variable used for items was changed in the code from "?item" to "?prob44item", but in the OPTIONAL clause, the ?item variable was not changed. The result is that d:item432 is returned as an instance of dm:prob44, as displayed on p. 131, even though this item had in fact been approved by a Supervisor at Job Grade 5. Change "?item" to "?prob44item" in the third UNION, and the correct results are returned.

Note from the Author or Editor:
Mark is correct about the problem and the proposed solution.

instead of "ab:i8301" it should be "d:i8301" and also same thing is used in subsequent lines.

Note from the Author or Editor:
This is in the three paragraphs of descriptive text following example ex013.rq. The report is correct.

In the RDF/XML example, the rdf:about value should say ns/data#item342 instead of ns/demo#item342.

Note from the Author or Editor:
Submitted myself, will fix.

rdfs:label should not be in the result of running ex092.rq with ex069.ttl.

Note from the Author or Editor:
Run it again and substitute the correct output.

Because Python has been updated with some backward-incompatible parts, the example at the bottom of this page does not work with the latest release of Python and should be updated.

Note from the Author or Editor:
update script