Re: [redland-dev] xpath query

Joe Andrieu Sun, 20 Jun 2010 11:05:38 -0700

I"m not sure which query module you're using, but with SPARQL, you would just get rid of the ?label term and use "City" instead. In fact, whatever the query engine, you can probably just use sprintf or something similar to construct the query clause with "City" in place of ?label.

Something like

char keyword[]="City";

char query_string[BIGENOUGHBUFFER];

sprintf(query_string, "select ?comment from <C:/datafile.rdf> where (?x rdf:type rdfs:Class) (?x rdfs:label \"%s\") (?x rdfs:comment ?comment) using rdf for <http://www.w3.org/1999/02/22-rdf-syntax-ns#>, rdfs for <http://www.w3.org/2000/01/rdf-schema#>", keyword);

I won't address the potential unicode and buffer overrun problems. I prefer c++ classes to deal with the buffer issues and haven't yet settled completely on how I'm handling unicode.

-j

Joe Andrieu
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+1 (805) 705-8651
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On 6/20/2010 4:11 AM, Jagdev Bhogal wrote:

Dear all

I have a c-program which currently parses an rdf file and retrieves all of the nodes using:

const char *query_string="select ?label, ?comment from <C:/datafile.rdf> where (?x rdf:type rdfs:Class) (?x rdfs:label ?label) (?x rdfs:comment ?comment) using rdf for <http://www.w3.org/1999/02/22-rdf-syntax-ns#>,rdfs for <http://www.w3.org/2000/01/rdf-schema#>";

Lets say I have a string defined as:

char keyword[]="City";

My question is can we have a where clause in the query, so that we only retrieve results where the strcmp(label, keyword) = 0 in other words only retrieve those results where the label is equal to the keyword which in this case is "City".

If further explanation is needed let me know.

Thank you

Jagdev

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Re: [redland-dev] xpath query

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