SPARQL select query with condition? - sparql

Question

I'm trying to form SPARQL query which will give Domain Names and Method Name against the given Java Class from below RDF. For e.g
Select DomainNames, MethodName where JavaClass = 'MyJavaClass'.
This is just a pseudo query. I need help in forming similar query in SPARQL. thanks.
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:DOL="http://www.MyOnt.com/something/v1#"
xmlns:DC="http://purl.org/dc/dcmitype/"
xmlns:foaf="http://xmlns.com/foaf/0.1/">
<rdf:Description rdf:about="http://www.MyOnt.com/something/data/MyJavaClass">
<DOL:belongsTo>
<rdf:Description rdf:about="http://www.MyOnt.com/something/data/MyDomain">
<DOL:domainName>MyDomainValue2</DOL:domainName>
<DOL:domainName>MyDomainValue</DOL:domainName>
</rdf:Description>
</DOL:belongsTo>
<DOL:hasMethod>
<rdf:Description rdf:about="http://www.MyOnt.com/something/data/MyMethod">
<DOL:returnType>MethodReturnType</DOL:returnType>
</rdf:Description>
</DOL:hasMethod>
<foaf:name>MyJavaClass</foaf:name>
</rdf:Description>
</rdf:RDF>

Answer 1

It's generally easier to understand what the SPARQL query should look like if you first put the data into Turtle, which has a syntax very similar to SPARQL. Here's what your data is in Turtle:
#prefix DOL: <http://www.MyOnt.com/something/v1#> .
#prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
#prefix foaf: <http://xmlns.com/foaf/0.1/> .
#prefix DC: <http://purl.org/dc/dcmitype/> .
<http://www.MyOnt.com/something/data/MyDomain>
DOL:domainName "MyDomainValue2" , "MyDomainValue" .
<http://www.MyOnt.com/something/data/MyJavaClass>
DOL:belongsTo <http://www.MyOnt.com/something/data/MyDomain> ;
DOL:hasMethod <http://www.MyOnt.com/something/data/MyMethod> ;
foaf:name "MyJavaClass" .
<http://www.MyOnt.com/something/data/MyMethod>
DOL:returnType "MethodReturnType" .
Once you've done that, the query looks almost exactly like the data, except with variables in it. The only catch here is that since you're looking for domains and methods, you need to use a union (assuming that you want to bind domains and methods as different variables).
prefix DOL: <http://www.MyOnt.com/something/v1#>
prefix foaf: <http://xmlns.com/foaf/0.1/>
select ?domain ?method {
?class foaf:name "MyJavaClass" .
{ ?class DOL:belongsTo ?domain }
union
{ ?class DOL:hasMethod ?method }
}
---------------------------------------------------------------------------------------------------
| domain | method |
===================================================================================================
| <http://www.MyOnt.com/something/data/MyDomain> | |
| | <http://www.MyOnt.com/something/data/MyMethod> |
---------------------------------------------------------------------------------------------------
If you're willing to have the domain and method bound to the same variable, you can use an alternation property path to select either a domain or a method:
prefix DOL: <http://www.MyOnt.com/something/v1#>
prefix foaf: <http://xmlns.com/foaf/0.1/>
select ?domainOrMethod {
?class foaf:name "MyJavaClass" ;
DOL:belongsTo|DOL:hasMethod ?domainOrMethod
}
--------------------------------------------------
| domainOrMethod |
==================================================
| <http://www.MyOnt.com/something/data/MyDomain> |
| <http://www.MyOnt.com/something/data/MyMethod> |
--------------------------------------------------
As another alternative, you could use a values block to specify the properties that you want to follow (hasMethod or belongsTo), in which case you can select that as well in order to know which type of value you have:
prefix DOL: <http://www.MyOnt.com/something/v1#>
prefix foaf: <http://xmlns.com/foaf/0.1/>
select ?property ?value {
values ?property { DOL:belongsTo DOL:hasMethod }
?class foaf:name "MyJavaClass" ;
?property ?value
}
------------------------------------------------------------------
| property | value |
==================================================================
| DOL:belongsTo | <http://www.MyOnt.com/something/data/MyDomain> |
| DOL:hasMethod | <http://www.MyOnt.com/something/data/MyMethod> |
------------------------------------------------------------------