Concatenate one column over a resultset like kind of group_concat

Question

I am currently writing on a SPARQL query (GraphDB) and try to concatenate the results of one column to avoid the kind of "duplicates".

My current query looks like this

SELECT ?label ?otaupdater
WHERE {
 ?charger rdf:type mymodel:SoftwarePackage. 
 ?charger mymodel:isCompatibleWith ?target.
 ?target car:CarId <93718293>.
 ?charger rdfs:label ?label.
 ?otaupdater rdf:type mymodel:OTAUpdater.
 ?charger mymodel:isCompatibleWith ?otaupdater.
}

which gives me a resultset like

label	otaupdater
Chargie_One	123
Chargie_One	456
Chargie_Two	123

I tried to work in the command group_concat but only got so far that I ended up with

SELECT (group_concat(?otaupdater; separator=", ") AS ?otaupdaters) where { ... }

but this only returns all otaupdaters in one builded list.

What I am trying to achieve is something like this:

label	otaupdaters
Chargie_One	123, 456
Chargie_Two	123

Answer 1

The comment of @UninformedUser lead to the answer:

SELECT ?charger ?label ?target (group_concat(?otaupdater; separator=", ") AS ?otaupdaters)
WHERE {
 ?charger rdf:type mymodel:SoftwarePackage. 
 ?charger mymodel:isCompatibleWith ?target.
 ?target car:CarId <93718293>.
 ?charger rdfs:label ?label.
 ?otaupdater rdf:type mymodel:OTAUpdater.
 ?charger mymodel:isCompatibleWith ?otaupdater.
}
GROUP BY ?charger ?label ?target