SPARQL group by and order by: not ordered

Question

I follow up on query where the schema.org database is used to find the number of children of a class - as a simpler database than my application. I want to get the names of the

Answer 1

An additional select subquery is required to push the order inside the groups:

prefix schema:  
prefix rdfs:    

select    ?child  (group_concat (?string) as ?strings) 

where {
    select * 
    {
     ?child  rdfs:subClassOf schema:Event .
     ?grandchild rdfs:subClassOf ?child .
     bind (strafter(str(?grandchild), "http://schema.org/") as ?string)
    } order by asc(?string)
}   group by ?child  
limit 20