PostgreSQL：函数返回多个记录集：如何在C＃中读取？

Question

Using this link http://www.sqlines.com/postgresql/npgsql_cs_result_sets I have created the example, but it does not work: There is my function:

 CREATE OR REPLACE FUNCTION show_cities_multiple() 
 RETURNS SETOF refcursor AS $$
    DECLARE
      ref1 refcursor; 
      ref2 refcursor;                             
    BEGIN
      OPEN ref1 FOR SELECT user_id, user_name FROM users;
      RETURN NEXT ref1; 

      OPEN ref2 FOR SELECT id, company FROM customers;
      RETURN NEXT ref2;      
    END;
    $$ LANGUAGE plpgsql;

The 1st loop reads recordsets names only and that is all what I can read from the function.

         NpgsqlConnection conn = new NpgsqlConnection(GetConnectionString());
                conn.Open();
                NpgsqlTransaction tran = conn.BeginTransaction();
                NpgsqlCommand command = new NpgsqlCommand("show_cities_multiple", conn);
                command.CommandType = CommandType.StoredProcedure;
                NpgsqlDataReader dr = command.ExecuteReader();
                while (dr.Read())
                {
                   Console.Write("{0}\n", dr[0]);
                }
// ----------there is output - only names of cursors recordsets
// <unnamed portal 1>
// <unnamed portal 2>

                dr.NextResult(); 
// But there is nothing to read, no additional recordsets
                while (dr.Read())
                    Console.Write("{0}\t{1} \n", dr[0], dr[1]);

                tran.Commit();
                conn.Close();

What is wrong? How to read multiple recordsets from a PGSQL function?

Answer 1

There are a few ways to work with cursors for different versions

how can I get cursor data with calling stored procedure in npgsql