[GENERAL] how to return results from code block

[Andrus]

How to return single row or results from code block executed using ADO.NET 
ExecuteQuery() method.
I tried 

DO $$
declare 
  i integer :=0;

begin
select i+1 as res1, i+2 as res2;
END$$;

but got error:

ERROR:  query has no destination for result data

How to return single row result from code pgsql  code block ?

Andrus.