rdf - SPARQL insert query not inserting -

when run sparql update:

insert {   graph <n4> {     ?s foaf:firstname ?o   } } {   graph <n1> {     ?s foaf:familyname ?o .     ?o foaf:familyname ?x   } } 

although syntactically fine, no results. because ?s insert clause can not bound ?s , ?o simultaneously?

your query syntactically fine sparql, patterns match probably, in cases, aren't legal rdf. in particular, it's unlikely pattern:

?s foaf:familyname ?o . ?o foaf:familyname ?x 

will ever match data. value of ?o string, rdf literal, , literals cannot subjects of triples in rdf, it's unlikely ?o foaf:familyname ?x can ever match. since means no triples match part of query, there's nothing insert. i'd suggest first run

select ?s ?o {   graph <n1> {     ?s foaf:familyname ?o .     ?o foaf:familyname ?x   } } 

to see values of ?s , ?o available insert. expect won't see results, , that's why you're not inserting triples n4.

as particular question asked,

is because ?s insert clause can not bound ?s , ?o simultaneously?

there's no issue simultaneous bindings. part of query produces (possibly empty) set of results, each of binds ?s, ?o, , ?x. then, each solution, values of ?s , ?o used construct triple value-of-s foaf:firstname value-of-o , of triples inserted n4. nothing getting inserted n4 because set of results empty (for reasons described above).