public static async Task InsertScoresAsync()

in applications/leaderboard/step6/Program.cs [209:278]
69 lines of code
5 McCabe index (conditional complexity)

        public static async Task InsertScoresAsync(
            string projectId, string instanceId, string databaseId)
        {
            string connectionString =
            $"Data Source=projects/{projectId}/instances/{instanceId}"
            + $"/databases/{databaseId}";

            // Insert 4 score records into the Scores table for each player
            // in the Players table.
            using (var connection = new SpannerConnection(connectionString))
            {
                await connection.OpenAsync();
                await connection.RunWithRetriableTransactionAsync(async (transaction) =>
                {
                    Random r = new Random();
                    bool playerRecordsFound = false;
                    SpannerBatchCommand cmdBatch = transaction.CreateBatchDmlCommand();
                    var cmdLookup = connection.CreateSelectCommand("SELECT * FROM Players");
                    cmdLookup.Transaction = transaction;
                    using (var reader = await cmdLookup.ExecuteReaderAsync())
                    {
                        while (await reader.ReadAsync())
                        {
                            playerRecordsFound = true;
                            for (int i = 0; i < 4; i++)
                            {
                                DateTime randomTimestamp = DateTime.Now
                                        .AddYears(r.Next(-2, 1))
                                        .AddMonths(r.Next(-12, 1))
                                        .AddDays(r.Next(-28, 0))
                                        .AddHours(r.Next(-24, 0))
                                        .AddSeconds(r.Next(-60, 0))
                                        .AddMilliseconds(r.Next(-100000, 0));
                                SpannerCommand cmdInsert =
                                connection.CreateDmlCommand(
                                    "INSERT INTO Scores "
                                    + "(PlayerId, Score, Timestamp) "
                                    + "VALUES (@PlayerId, @Score, @Timestamp)",
                                    new SpannerParameterCollection {
                                        {"PlayerId", SpannerDbType.Int64},
                                        {"Score", SpannerDbType.Int64},
                                        {"Timestamp",
                                            SpannerDbType.Timestamp}});
                                cmdInsert.Parameters["PlayerId"].Value =
                                    reader.GetFieldValue<int>("PlayerId");
                                cmdInsert.Parameters["Score"].Value =
                                    r.Next(1000, 1000001);
                                cmdInsert.Parameters["Timestamp"].Value =
                                    randomTimestamp.ToString("o");
                                cmdBatch.Add(cmdInsert);
                            }
                        }
                        if (!playerRecordsFound)
                        {
                            Console.WriteLine("Parameter 'scores' is invalid "
                            + "since no player records currently exist. First "
                            + "insert players then insert scores.");
                            Environment.Exit((int)ExitCode.InvalidParameter);
                        }
                        else
                        {
                            await cmdBatch.ExecuteNonQueryAsync();
                            Console.WriteLine(
                                "Done inserting score records..."
                            );
                        }
                    }
                });
            }
        }