DataAccessLayer.DataBase.GetIdByName C# (CSharp) Метод

        public Guid GetIdByName(string login)
        {
            string queryString =
               "SELECT [dbo].accounts.accountid " +
               "FROM [dbo].accounts " +
               "WHERE (login = @login);";

            using (SqlConnection connection = new SqlConnection(_connectionString))
            {
                var command = new SqlCommand(queryString, connection);

                command.Parameters.AddWithValue("login", login);

                connection.Open();
                var reader = command.ExecuteReader();

                if (reader == null)
                    return Guid.Empty;
                Guid guid = Guid.Empty;
                while (reader.Read())
                    guid = (Guid)reader[0];
                return guid;
            }
        }