private async Task UsersRefresh()
{
	var x=db_func.GetUsers();
	dgvUsers.DataSource =x;
}

public async Task<List<User>> GetUsersAsync()
        {
            List<User> ulist = new List<User>();
            DataTable dt = await SelectAsync("select_users", null);
            foreach (var dr in dt.Select())
            {
                ulist.Add(new User(new Guid(dr["user_id"].ToString()), dr["user_name"].ToString()));;
            }
            return ulist;
        }

public async static Task<DataTable> SelectAsync(string procname, NpgsqlParameterList param = null)
        {
            var table = new DataTable();
            if (pg.IsConnect)
            {
                try
                {
                    using (NpgsqlCommand command = conn.CreateCommand())
                    {
                        command.CommandText = procname;
                        command.CommandType = CommandType.StoredProcedure;
                        if (param != null)
                            command.Parameters.AddRange(param.ToArray());
                        var reader = await command.ExecuteReaderAsync();
                        for (int i = 0; i < reader.FieldCount; i++)
                            table.Columns.Add(reader.GetName(i));
                        while (await reader.ReadAsync())
                        {
                            var row = table.NewRow();
                            for (int i = 0; i < reader.FieldCount; i++)
                                row[i] = reader[i];
                            table.Rows.Add(row);
                        }
                    }
                }
                catch (NpgsqlException e)
                {
                    e.Handle();
                }
            }
            return table;
        }

private async Task UsersRefresh()
        {
            var x = await db_func.GetAppUsersAsync();
            dgvUsers.DataSource = x;
        }