SPARQL : how to get values for a particular resource? - sparql

Question

I am trying this query:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?label
WHERE
{
?AGE rdfs:label ?label.
}
I need all the values of AGE from my model but instead this query is giving me other resources values which have the same property label .
For example I have connected the resource gender to have a property rdfs:label. So in my result I get both age values and gender values.
Can anybody tell me where am I wrong ?

Answer 1

It seems you may be assigning some semantics to the variable '?AGE'. SPARQL is a graph pattern matching language and anything with a '?' as the first character is a variable - or better yet, an unknown in the graph pattern match. I.e., the following is an equivalent query to yours:
SPARQL ?label
WHERE
{ ?s rdfs:label ?label .
}
This will find all triples that have a rdfs:label property and select the value of ?label.
If you have a specific resource you want to query, then specify that resource in the subject, for example:
PREFIX ex: <http://example.org/ex>
SPARQL ?label
WHERE
{ ex:AGE rdfs:label ?label .
}
So understanding the difference between an unknown (denoted by '?' (or '$')) and a known (a qname or a full URI) is important to understand how SPARQL performs graph pattern matching.
Lots of SPARQL learning material on the Web, so a suggestion is to look into some of these to learn some basics.