How to write code in C #, to add new data to the database

Adding triplets to GraphDB

SparqlRemoteEndpoint endpoint = new SparqlRemoteEndpoint(new Uri("http://localhost:7200/sparql"), "http://localhost:7200/");
SparqlResultSet results = endpoint.QueryWithResultSet("PREFIX : <http://www.example.org/> INSERT DATA {:test :test :hhrh }");

why does not it work?

StardogConnector stardog = new StardogConnector("http://localhost:7200", "test", "admin", "posw");
stardog.Begin();
string query = "PREFIX : <http://www.example.org/>SELECT * WHERE {:" + line[0] + " ?k :" + line[1] + "}";
stardog.Query(query);
stardog.Commit();

another way, same problem. Created a DB on a lokalka

Yes, I also came to this conclusion, I use GraphDB for the first time. Well, how can I implement it with a file? I wrote such code.

IGraph g = new Graph();

string sql = "PREFIX : <http://www.example.org/> INSERT DATA {:test :test :hhrh }";
g.LoadFromFile("t.n3"); 

Object results = g.ExecuteQuery(sql);

here comes such an error

VDS.RDF.Parsing.RdfParseException
HResult = 0x80131500
Message = [InsertKeywordToken at Line 1 Column 36 to Line 1 Column 42] Unexpected Token encountered - expected a BASE / PREFIX directive or a Query Keyword to start a Query
Source = dotNetRDF
Stack trace:
in VDS.RDF.Parsing.SparqlQueryParser.ParseInternal (SparqlQueryParserContext context)
in VDS.RDF.Parsing.SparqlQueryParser.ParseInternal (TextReader input)
in VDS.RDF.Parsing.SparqlQueryParser.ParseFromString (String queryString)
in VDS.RDF.GraphExtensions.ExecuteQuery (IGraph g, String sparqlQuery)
in algorAutoText.Program.Main (String [] args) in C: \ Users \ Denis \ source \ repos \ algorAutoText \ algorAutoText \ Program.cs: line 43

judging by mistake, I supposedly did not add BASE / PREFIX. But he is in the request

Update and delete queries come through the /statements endpoint,

i.e. /repositories/{repository_id}/statements.

You can see the RDF4J server REST API here:

http://docs.rdf4j.org/rest-api/#_the_rdf4j_server_rest_api